Luna
* Every hero that can withstand or prevent Eclipse at level 7: 
Juggernaut, 
Riki, 
Clockwerk, 
Drow Ranger, 
Abaddon, 
Faceless Void, 
Weaver, 
Outworld Destroyer.
Legion Commander
* If he isn't broken (break), Abaddon can use Borrowed Time to waste Legion Commander's 
Duel, As Borrowed Time has a shorter cooldown, Legion Commander can't win duels, effectively reducing her targets by one, Duel also means that Borrowed Time heals Abaddon for the duration of the duel, as Legion can't stop attacking.
Additional:
* 
Aphotic Shield and 
Mist Coil makes it hard for Legion Commander to kill Abaddon's teammates in Duels.
* 
Borrowed Time makes Abaddon nearly impossible to kill in Duels, and often replenishes much of his health because Legion Commander cannot manually stop attacking during Duels.
Luna
* Every hero that can withstand or prevent Eclipse at level 7: Juggernaut, Riki, Clockwerk, Drow Ranger, Abaddon, Faceless Void, Weaver, Outworld Destroyer.
Legion Commander
* Battery Assault's mini-stuns can severely disrupt Legion Commander's attack animation when she enters a Duel, potentially saving Clockwerk (or his allies) and possibly even giving him an edge in securing a win himself.
* Power Cogs pushes Legion Commander away from Clockwerk's allies when she enters a Duel.
Luna
* Every hero that can withstand or prevent Eclipse at level 7: Juggernaut, Riki, Clockwerk, Drow Ranger, Abaddon, Faceless Void, Weaver, Outworld Destroyer.
Legion Commander
* 
Astral Imprisonment prevents Legion Commander from killing her opponents in Duels.
Additional:
* Outworld Destroyer can save an ally hero caught by Duel with Astral Imprisonment, and he can inflict heavy damage on Legion Commander with Arcane Orb to aid his ally. However, if he gets caught, he is unlikely to survive the duel, due to his lack of durability.
Luna
* Zeus's highly damaging nuke spells with low cooldowns is not something Luna can go against, though Luna can win against Zeus in late game.
* 
Thundergod's Wrath can be used before a fight to harm Luna before she activates 
Black King Bar, reducing her survivability for that fight.
* For the same reasons, Zeus makes a very powerful ally for Luna when they are in the same team.
Legion Commander
* Heroes with global abilities can give Legion Commander's opponent an edge in Duels from anywhere on the map: 
Nature's Prophet, 
Ancient Apparition, 
Zeus, 
Invoker, 
Treant Protector
Luna
* All assassin-type carries in a one against one situation: 
Meepo, 
Phantom Assassin, Riki, 
Ursa. Luna's only chances are that she buys 
Ethereal Blade or Black King Bar to gain a slight edge against them, or both items if necessary.
Legion Commander
* 
Fury Swipes can give Ursa the edge in Duels.
* 
Enrage's instant cast time allows it to be used before Legion Commander initiates a Duel, causing Ursa to take almost no damage for a brief period of time.
* However, Duel stops Ursa from casting Enrage at the most critical moment
Luna
* Despite Ancient Apparition's fragileness, he can easily harass Luna on lane with 
Chilling Touch due to it's high range and damage. This can get even worse if Ancient Apparition buys 
Aghanim's Scepter and combines it with items that can give him bonus attack damage and attack speed.
* Chilling Touch combined with 
Ice Vortex can make it difficult for Luna to escape from 
Cold Feet
* 
Ice Blast can nullify any healing Luna receives and any attempt for her to save herself with 
Satanic, even through Black King Bar.
* For the same reasons, Ancient Apparition makes a very powerful ally for Luna when they are in the same team.
Legion Commander
* Heroes with global abilities can give Legion Commander's opponent an edge in Duels from anywhere on the map: Nature's Prophet, Ancient Apparition, Zeus, Invoker, Treant Protector
Luna
* A couple of nukers and disablers on the same lane can finish a squishy Luna efficiently despite a teammate's assistance: 
Sven + 
Shadow Shaman.
Legion Commander
* 
God's Strength makes Sven one of the worst heroes to Duel.
* 
Storm Hammer can be used to interrupt Duels.
* 
Warcry gives a big boost in passive defensive ability with the active component to nearby allies.
* With the Aghanim Shard Warcry also gives nearby allies passive increases.
Luna
* Even though Moon Glaives can bounce between Meepo and his clones, Meepo can tank Eclipse because of his clones.
* 
Earthbind takes away Luna's mobility advantage.
* Meepo can shutdown Luna's split-push ability with his global presence.
Legion Commander
* When Legion Commander uses Duel on one Meepo, he can use his other Meepos to kill her. If he wasn't dueled, he can help the teammate who was duelled to give the teammate the damage instead of Legion Commander.
* However, if Legion Commander picked up an Aghanim's Scepter and she duels one Meepo, that might be the end of Meepo if Legion managed to gather enough damage from previous duels.
Luna
* Illusions and summons are double-edge sword type of matchup for Luna. On one hand, they can tank damage from Eclipse, but on the other hand, she can easily clear them before Eclipse with Moon Glaives. Examples include 
Spectre, 
Shadow Demon, 
Phantom Lancer, 
Naga Siren, 
Chaos Knight, 
Terrorblade) or bring other units into the fight (such as Nature's Prophet, 
Lone Druid, 
Chen, 
Enchantress, Meepo and 
Arc Warden).
Luna
* Lina has very high magic burst damage to use against the low-health-pool Luna. 
Laguna Blade can also be upgraded with Laguna Blade damage is Pure and pierces Spell Immunity to bypass Black King Bar, making Lina even more of a threat. Luna however, can easily counter this problem with 
Linken's Sphere, which is a common item for her.
* For the same reasons, Lina makes a very powerful ally for Luna when they are in the same team.
Legion Commander
* 
Static Link drains Legion Commander's accumulated damage, effectively neutralizing her overall primary advantage, and prevents her from winning Duels.
* 
Storm Surge's movement speed buff makes Razor and his allies harder to catch and initiate.
* 
Eye of the Storm, if used beforehand, will always hit Legion Commander during Duels, due to her forced proximity. This drastically lowers her survivability during Duel.
Luna
* 
Burrowstrike allows Sand King to escape from 
Eclipse or to close the gap on Luna and finish her off.
* 
Sand Storm allows Sand King to harass Luna more efficiently than she does with 
Lucent Beam, as it makes him invisible for it's duration and while in it, rendering him safe from both, Lucent Beam and Eclipse and forcing Luna to buy 
Dust of Appearance more often.
* 
Caustic Finale allows Sand King to deal serious damage to both, Luna and her allies, which is especially hazardous in laning stage as Luna's attack range is short.
* 
Epicenter combined with Burrowstrike and Sand Storm can often kill Luna before she can do anything because of her low health and strength gain.
* Overall, Sand King forces Luna to play more defensively instead of offensively, and for the same reasons, Sand King makes a very powerful ally for Luna when they are in the same team.
Additional:
* Burrowstrike allows Sand King to escape from Eclipse or to close the gap on Luna and finish her off.
* Sand Storm allows Sand King to harass Luna more efficiently than she does with Lucent Beam, as it makes him invisible for it's duration and while in it, rendering him safe from both, Lucent Beam and Eclipse and forcing Luna to buy Dust of Appearance more often.
* Caustic Finale allows Sand King to deal serious damage to both, Luna and her allies, which is especially hazardous for Luna during the laning stage as Luna's attack range is short.
* Epicenter combined with Burrowstrike and Sand Storm can often kill Luna before she can do anything because of her low health and strength gain.
* Overall, Sand King forces Luna to play more defensively instead of offensively, and for the same reasons, Sand King makes a very powerful ally for Luna when they are in the same team.
Luna
* 
Demonic Purge takes off Luna's superior mobility, removing the need for chasing her and allowing your team to reposition in team fights or escape when at low HP. If Shadow Demon has Aghanim's Scepter it will also take away glaive bounces and extra damage from Luna's passive. And Luna's commonly items Manta Style and Black King Bar does not work dispell to Demonic Purge
* Luna's illusions created by Disruption are very valuable with their 
Moon Glaives. These will effectively counter her pushing attempts and are painfully effective in team fights.
* Disruption can be used to save an ally from Eclipse.
* For the same reasons, Shadow Demon makes a very powerful ally for Luna when they are in the same team.
Additional:
* Demonic Purge takes off Luna's superior mobility, removing the need for chasing her and allowing your team to reposition in team fights or escape when at low HP. If Shadow Demon has Aghanim's Sceptre it will also take away glaive bounces and extra damage from Luna's passive.
* Luna's illusions created by Disruption are very valuable with their Moon Glaives. These will effectively counter her pushing attempts and are painfully effective in team fights.
* Disruption can be used to save an ally from Eclipse.
* For the same reasons, Shadow Demon is a very good ally for Luna when they are in the same team.
Legion Commander
* Heroes who can hide the Dueled target (Outworld Destroyer, Shadow Demon, 
Tusk, 
Phoenix with Aghanim's Scepter etc).
Additional:
* Disruption can save allies and mess up an initiation from an enemy Legion Commander. Using Disruption on your ally that is affected by Duel will leave her totally exposed without the benefit of the life steal from 
Moment of Courage. A precise decision to Disrupt Legion Commander or her victim is crucial to waste Duel's potential.
* Demonic Purge cannot be dispelled by a hard dispel from 
Press the Attack, which in turn can be dispelled by your ultimate.
Luna
* Illusions and summons are double-edge sword type of matchup for Luna. On one hand, they can tank damage from Eclipse, but on the other hand, she can easily clear them before Eclipse with Moon Glaives. Examples include Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden).
Legion Commander
* 
Mystic Flare can easily burst down Legion Commander while she is Dueling.
Luna
* Even though Luna can easily kill Jakiro in few strikes, he can also do the same to her is she is not careful.
* 
Dual Breath and 
Liquid Fire allow Jakiro to harass Luna more efficiently than she can harass Jakiro with her Lucent Beam.
* Jakiro can save his allies from Luna during her attempts to use Eclipse by casting 
Ice Path on Luna.
* Aghanim's Scepter upgraded 
Macropyre can deal pure damage-over-time and pierce spell immunity, which can make it very hard for Luna to be in teamfights without suffering too many damage.
* For the same reasons, Jakiro makes a very powerful ally for Luna when they are in the same team.
Additional:
* Even though Luna can easily kill Jakiro in few strikes, he can also do the same to her is she is not careful.
* Dual Breath and Liquid Fire allow Jakiro to harass Luna more efficiently than she can harass Jakiro with her Lucent Beam.
* Jakiro can save his allies from Luna during her attempts to use Eclipse by casting Ice Path on Luna.
* Aghanim's Scepter upgraded Macropyre can deal pure damage-over-time and pierce spell immunity, which can make it very hard for Luna to be in teamfights without suffering too many damage.
* For the same reasons, Jakiro makes a very powerful ally for Luna when they are in the same team.
Legion Commander
* 
Shallow Grave prevents Legion Commander from killing her opponents in Duels.
* 
Shadow Wave will heal an ally caught in a Duel, as well as dealing damage to Legion Commander.
Luna
* Heroes who cannot fight back during Arena of Blood in the early and mid game: Abaddon, 
Anti-Mage, 
Broodmother, 
Luna, 
Sniper, 
Troll Warlord, Weaver, 
Clinkz.
Legion Commander
* Because Duel requires both combatants to face each other, 
Bulwark's effectiveness will be increased by a huge margin, which makes it much more difficult for Legion Commander to win any duels against him.
* 
Spear of Mars and 
God's Rebuke pushes Legion Commander away during Duels against allies.
Additional:
* Bulwark immensely mitigates Duel, even with bonus physical damage, as Bulwark scales by percentage. Mars can also buy time for a dueled ally by pushing Legion Commander away with Spear of Mars.
Legion Commander
* 
Legion Commander is both good and bad vs Mars, on the plus side she can dispel Spear of Mars with Press the Attack and is a good 
Silver Edge carrier. However, Mars is not an ideal Duel target, as Bulwark will force her to 1: Buy Silver Edge, and 2: Hit Mars with it before the Duel, allowing a skilled Mars to react, especially with 
Eul's Scepter of Divinity. In teamfights, Mars will happily draw attention after using his abilities, and tank the Duel with all spells on cooldown.
Legion Commander
* 
Lucky Shot can disarm Legion Commander and reduce her armor, which can reduce her chances of winning a duel. If an ally is targeted, Pangolier can simply use 
Swashbuckle to inflict it on her.
* If an enemy Pangolier casts a well-timed 
Rolling Thunder before Legion Commander can cast Duel, it might result in her chasing down Pangolier until his or her ultimate ends, whichever duration ends first, resulting in an open window for enemy allies to target Legion Commander, making her vulnerable and susceptible to any source of attacks. If Legion Commander has an Aghanim's Scepter in her inventory, the risk of wasting a solid 8 seconds would result in a futile duel.
* Dueling Pangolier is normally a mistake, Pangolier can disarm you in the duel, and potentially gain some Duel damage, Only duel Pangolier if at least 1 ally is nearby, and he is on low health, And even then, be wary, A good duel can easily turn against you with one Lucky Shot (Due to Lucky Shot lasting 4 seconds).
Additional:
* Swashbuckle can be used to disarm Legion Commander while she is Dueling an ally, granting her opponent a considerable advantage, Lucky Shot lasts 4 seconds at most wasting Legion Commander's entire Duel, (Or half, if Legion Commander has the Scepter).
* Legion Commander will try not to duel Pangolier alone, as she will almost inevitably lose, thanks to Lucky Shot's disarm, If Legion Commander wants to duel a Pangolier, she must be with atleast a teammate, and if she has her scepter, 3 or 4 teammates.
* Legion Commander is often with her allies, allowing you to rack up some considerable damage resistance with Shield Crash.
Luna
* Primal Beast has a massive healthpool making it very difficult to get through it with a nuke such as Eclipse or Lucent Beam.
* Primal Beast is faster than Luna, as one of her main ways to escape danger, is very problematic for her in the laning stage especially.
* His ultimate goes through debuff immunity, making Luna's Black King Bar less effective.
* Primal Beast commonly buys 
Blade Mail which is a big problem for a single target bursting hero like Luna.
Legion Commander
* Heroes who can hide the Dueled target (Outworld Destroyer, Shadow Demon, Tusk, Phoenix with Aghanim's Scepter etc).
Additional:
* Legion Commander relies on her powerful attack and her Duel to be effective. But if Phoenix gets the jump on her first, she can find herself severely slowed, taking heavy damage, and find herself unable to Duel a burning Supernova.
* It must be noted that Press the Attack will both dispel the attack slow of Fire Spirits and grant her or whoever she targets bonus attack speed. This allows her to easily destroy a Supernova if caution is not taken to prevent this from occurring. As such, it would be a better decision to simply avoid a farmed or skilled Legion Commander instead of attempting to overpower her.
* If an ally is caught by Duel, Phoenix can use Sun Ray to heal the ally and damage Legion Commander, possibly swinging the Duel in their team's favor. Or with Aghanim's Scepter, Phoenix can save an ally from dying in Duel with Supernova and cancel the Duel as well.
Luna
* Escape-type carries: 
Slark, 
Storm Spirit, Weaver.
Luna
* Hard-hitters who relies mostly on raw stats or good passive and therefore make a perfect target for 
Dark Portrait: Naga Siren, Faceless Void, Terrorblade, Luna, Anti-Mage
Legion Commander
* Troll Warlord's melee bash and high attack speed can often help him and his allies win Duels against Legion Commander.
Legion Commander
* Heroes with global abilities can give Legion Commander's opponent an edge in Duels from anywhere on the map: Nature's Prophet, Ancient Apparition, Zeus, Invoker, Treant Protector
Luna
* Heroes that can keep Luna locked down for a long time can be a threat (she is very item and spell dependent): Faceless Void, Legion Commander, 
Doom.
Legion Commander
* Heroes who can hide the Dueled target (Outworld Destroyer, Shadow Demon, Tusk, Phoenix with Aghanim's Scepter etc).
Additional:
* Walrus PUNCH! makes Legion Commander lose Duel easily, especially when she doesn't have Blade Mail. Tusk can also snowball dueled allies, preventing them from taking damage for a large portion of the duel's duration.
Legion Commander
* 
Fate's Edict prevents Legion Commander from attacking for a few seconds, potentially saving Oracle's ally.
* 
Fortune's End dispels Press the Attack's healing and attack speed buff, as well as the movement speed bonus from Overwhelming Odds.
* 
False Promise protects allies and prevents Legion Commander from winning Duels and gaining bonus damage.
Additional:
* Provided that the enemy team does not have an 
Axe, Oracle can guarantee that his ally survives for the duration of the Duel with False Promise and has decent nuke potential to help ally to win a Duel. He can also disarm Legion Commander with Fate's Edict.
* Oracle can dispel enemy buffs like 
Overwhelming Odds and Press the Attack with Fortune's End.
Legion Commander
* Heroes with long disables, like 
Lion, 
Night Stalker, or Legion Commander, can prevent Oracle from using spells or items.
Legion Commander
* Solar Guardian can save allies who are being dueled and will interrupt her Duel initiation.
Luna
* Luna can easily cancel channeling spells with Lucent Beam and 0.25s Eclipse Lucent Ministun talent for Eclipse, she can also buy 
Abyssal Blade in case they decide to buy Black King Bar: 
Enigma's 
Black Hole, 
Witch Doctor's 
Death Ward, Shadow Shaman's 
Shackles, Lion's 
Mana Drain, 
Bane's 
Fiend's Grip, 
Pudge's 
Dismember, 
Crystal Maiden's 
Freezing Field, 
Pugna's 
Life Drain, 
Dawnbreaker's 
Solar Guardian, and Naga Siren's 
Reel In from Aghanim's Scepter.
Legion Commander
* 
Paralyzing Cask can save ally from Legion Commander Duel's until she purchases Aghanim's Scepter.
* 
Voodoo Restoration can heal Witch Doctor allies from Duel's.
* Death Ward can help Witch Doctor allies from winning Duel's, if, he is not a target.
Luna
* Luna can easily cancel channeling spells with Lucent Beam and 0.25s Eclipse Lucent Ministun talent for Eclipse, she can also buy Abyssal Blade in case they decide to buy Black King Bar: Enigma's Black Hole, Witch Doctor's Death Ward, Shadow Shaman's Shackles, Lion's Mana Drain, Bane's Fiend's Grip, Pudge's Dismember, Crystal Maiden's Freezing Field, Pugna's Life Drain, Dawnbreaker's Solar Guardian, and Naga Siren's Reel In from Aghanim's Scepter.
Additional:
* Lucent Beam interrupts Death Ward from a decent range.
* With Dust of Appearance, Eclipse kills Witch Doctor during Death Ward, even through 
Glimmer Cape.
Legion Commander
* Invoker's spells will disable and destroy Legion Commander while she's locked in a Duel.
Legion Commander
* Heroes with long lockdowns: Shadow Shaman, Legion Commander.
Legion Commander
* With armor items like 
Solar Crest or 
Assault Cuirass combined with Bash of the Deep, Slardar can easily tank the Duel, If not dueled himself, he can drop Legion Commander's armor during duel and/or buff his teammate and save them, leaving her only the choice of dueling supports which can also be saved with fast Blink into Slithereen Crush.
Luna
* Illusion heroes like the aforementioned Phantom Lancer or Naga Siren, or heroes that tend to buy 
Manta Style, like Luna or Juggernaut, will give Slardar a hard time, as his damage is single-targeted.
Luna
* 
Shadow Dance prevents Luna from damaging Slark, and together with Silver Edge he can easily chase her or escape from her.
* Luna has no way to escape from 
Pounce's leash, which is especially bad as she is not used to buying 
Wind Waker, which is the only way to escape from Pounce outside of Black King Bar.
* For the same reasons, Slark makes a very powerful ally for Luna when they are in the same team.
Additional:
* Luna's lack of mobility and escape abilities makes her easily to gank for Slark.
* Shadow Dance helps avoid all the damage from Eclipse.
* For the same reasons, Slark makes a very powerful ally for Luna when they are in the same team.
Luna
* With Dust of Appearance, Luna will be able to use Eclipse on invisible heroes. Be mindful that Slark is exception because he'll be able to remove the debuff with 
Dark Pact.
Luna
* 
Telekinesis allows Rubick and his team to coordinate a gank on Luna early on. And just like 
Aghanim's Shard upgraded Dismember, Aghanim's Shard upgraded Telekinesis can also allow Rubick to save an allied hero from being killed by Eclipse.
* 
Fade Bolt allows Rubick to harass Luna on lane and weaken her attack damage early on.
* Both, Lucent Beam and Eclipse are very useful for Rubick to steal with 
Spell Steal, Luna's only way to counter this is with 
Lunar Orbit. Rubick can also use them from further distances than Luna thanks to 
Arcane Supremacy that increases his cast range and when he gets Aghanim's Scepter.
Additional:
* Lucent Beam is a solid magic nuke with a stun.
* Aghanim's Shard upgraded Lucent Beam gives Rubick bonus damage whenever he uses it
* Eclipse can output massive damage if casted by 
Rubick.
* Rubick has a good chance to steal Eclipse since Luna has only two cast abilities.
* Aghanim's Scepter greatly increase the effectiveness of the ability, with more damage as well as extended cast range.
* For the same reasons, Rubick also makes a good ally for Luna when they are in the same team.
Legion Commander
* Heroes with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, 
Lich, 
Techies, Rubick
Luna
* Aggressively blinking is not going to end well against Luna, because Queen of Pain will be an easy target for Lucent Beam & Eclipse.
* Queen of Pain's HP is abysmal, so Luna can quickly kill Queen of Pain as soon as she initiates with Blink.
Additional:
* Aggressively blinking is not going to end well against Luna, because Queen of Pain will be an easy target for Lucent Beam & Eclipse.
* Queen of Pain's HP is abysmal, so Luna can quickly kill Queen of Pain as soon as she initiates with Blink.
Legion Commander
* Duels prevents Queen of Pain from using Blink, which may force her to purchase a Linken's Sphere
* Because Queen of Pain is also not a right-click hero, Legion won't have much difficulties in duels.
* Press the Attack dispels Shadow Strike's debuff.
Luna
* Lucent Beam allows Luna to easily cancel Freezing Field.
* Without Black King Bar protection, Lucent Beam and Eclipse can make a short work out of Crystal Maiden's abysmal health.
* Skilled Luna will always buy Dust of Appearance, allowing her team to have a vision on Crystal Maiden while invisible and during channeling Freezing Field.
* Even with Black King Bar, Luna can still inflict considerable damage on Crystal Maiden with her attacks, which get empowered with Moon Glaives and 
Lunar Blessing, also smart and skilled Luna will buy Abyssal Blade to cancel Freezing Field even through Black King Bar in case of emergency. And since Crystal Maiden rarely buys Linken's Sphere, this can be a very big problem for her.
Additional:
* Lucent Beam allows Luna to easily cancel Freezing Field.
* Without Black King Bar protection, Lucent Beam and Eclipse can make a short work out of Crystal Maiden's abysmal health.
* Skilled Luna will always buy Dust of Appearance, allowing her team to have a vision on Crystal Maiden while invisible and during channeling Freezing Field.
* Even with Black King Bar, Luna can still inflict considerable damage on Crystal Maiden with her attacks, which get empowered with Moon Glaives and Lunar Blessing, also smart and skilled Luna will buy Abyssal Blade to cancel Freezing Field even through Black King Bar in case of emergency. Forcing Crystal Maiden to buy Linken's Sphere.
Legion Commander
* Duel is a great initiation to target Crystal Maiden with, as it prevents her from using Freezing Field or any other abilities and allowing the enemy team to quickly kill her before she can aid her team in a fight.
Luna
* Although Anti-Mage can survive Luna's magical damage output with 
Counterspell, Luna's physical damage from Moon Glaives and Lunar Blessing can be fair enough to deal with him.
* Reckless use of 
Blink will allow Luna Eclipse can finish off Anti-Mage from early-to-mid stages of the game until Anti-Mage gets Manta Style, Aghanim's Scepter that will give him access to 
Blink Fragment and Aghanim's Shard which will allow Counterspell to weaken enemy spell damage.
* However, Luna needs to finish the match as quickly as possible, because Anti-Mage is a hero who has a big advantage in longer matches once he farms items he needs for teamfights.
Legion Commander
* Duel renders Anti-Mage's escape capabilities with Blink and Counterspell useless. Blade Mail and Moment of Courage work well against Anti-Mage's relatively low health.
* A good initiation from Legion Commander and her team is enough to effortlessly kill Anti-Mage.
Additional:
* Counterspell offer no protection against Duel at all.
* Duel locks down Anti-Mage for a long duration, preventing him from escaping with Blink. One successful Duel initiation is usually enough for Legion Commander's team to kill Anti-Mage.
Luna
* Even though Luna has a hard time laning against Viper due to 
Nethertoxin being able to disable Moon Glaives and Lunar Blessing, Luna can take out Viper once she builds either Black King Bar or Silver Edge which will allow her to attack Viper freely.
* Eclipse can often finish off Viper from early-to-mid stages of the game before he can retaliate as 
Corrosive Skin gives little magic resistance to him early on.
* Manta Style is an item that Luna commonly buys in most of the games, which lets her disjoint 
Viper Strike. Additionally, illusions from Manta Style can make Viper waste time attacking them.
Additional:
* Even though Luna has a hard time laning against Viper due to Nethertoxin being able to disable Moon Glaives and Lunar Blessing, Luna can take out Viper once she builds either Black King Bar or Silver Edge which will allow her to attack Viper freely.
* Eclipse can often finish off Viper from early-to-mid stages of the game before he can retaliate as Corrosive Skin gives little magic resistance to him early on.
* Manta Style is an item that Luna commonly buys in most of the games, which lets her disjoint Viper Strike. Additionally, illusions from Manta Style can make Viper waste time attacking them.
Legion Commander
* Viper's frailty and low mobility make him an enticing Duel target and Corrosive Skin doesn't protect him against Legion Commander physical attacks.
* Press the Attack can dispel 
Poison Attack.
* Viper slows can easily negate by Overwhelming Odds movement speed.
Luna
* Even though Nyx Assassin can easily kill Luna with his high burst damage, Luna can also do the same to him if he is not careful.
* Lucent Beam can deal a fair amount of damage to Nyx Assassin if he has no 
Spiked Carapace available to use. Although Luna should be patient using Lucent Beam on Nyx Assassin when he uses Spiked Carapace.
* As Luna commonly buys Black King Bar, she can use it to freely attack Nyx Assassin whenever he tries to defend himself with Spiked Carapace during teamfights. Luna can also buy 
Eye of Skadi and Manta Style to survive Nyx Assassin's burst damage and distract him.
* Though 
Vendetta can deal serious damage to Luna and avoid Eclipse, smart Luna will always buy Dust of Appearance to provide vision on Nyx Assassin to her and her team.
Additional:
* Even though Nyx Assassin can easily kill Luna with his high burst damage, Luna can also do the same to him if he is not careful.
* Lucent Beam can deal a fair amount of damage to Nyx Assassin if he has no Spiked Carapace available to use. Although Luna should be patient using Lucent Beam on Nyx Assassin when he uses Spiked Carapace.
* As Luna commonly buys Black King Bar, she can use it to freely attack Nyx Assassin whenever he tries to defend himself with Spiked Carapace during teamfights. Luna can also buy Eye of Skadi and Manta Style to survive Nyx Assassin's burst damage and distract him.
* Though Vendetta can deal serious damage to Luna and avoid Eclipse, smart Luna will always buy Dust of Appearance to provide vision on Nyx Assassin to her and her team.
Legion Commander
* Duel's long duration prevents Nyx Assassin escaping from Vendetta. With Aghanim's Scepter, she can also bypass Spiked Carapace.
Luna
* Moon Glaives can ignore certain abilities that either trigger on attack or give evasion under the condition that the heroes who have them are not primary targets. Examples include: 
Centaur Warrunner, 
Windranger, Phantom Assassin, 
Hoodwink etc.
Legion Commander
* Press The Attack can save her allies dispels the stun from Shackleshot.
* Duel can lock down Windranger before she can escape with Windrun.
* Legion Commander tends to go for Blade Mail, which returns the damage she takes from Focus Fire.
Luna
* Even though Luna is the kind of hero that Bounty Hunter can handle due to Shadow Walk rendering him safe from Eclipse, smart Luna will always buy Dust of Appearance, allowing her to provide vision on him to her team, and possibly, kill Bounty Hunter with Eclipse.
Legion Commander
* Legion Commander with Press the Attack
* Heroes that can remove the Track debuff with their skills:
* Abaddon with Aphotic Shield and Borrowed Time
* 
Huskar with 
Life Break
* Juggernaut with 
Blade Fury
* Legion Commander with Press the Attack
* 
Lifestealer with 
Rage and 
Infest
* Naga Siren with 
Mirror Image
* 
Omniknight with 
Heavenly Grace
* 
Oracle with Fortune's End and False Promise
* Phantom Lancer with 
Doppelganger
* Slark with Dark Pact
* Ursa with Enrage
* Weaver with 
Time Lapse
* 
Tidehunter with 
Kraken Shell when damage received reaches the threshold.
Luna
* Heroes that create illusions: Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Luna
* If carefully timed, Aghanim's Scepter upgraded Eclipse combined with 0.2s Eclipse Lucent Ministun talent can quickly finish off Terrorblade before he can get a chance to save himself with 
Sunder due to its high magical damage as long as Terrorblade has no Black King Bar.
* Moon Glaives allows Luna to clear Terrorblade's illusions from both, Conjure Image and Manta Style, this can be particularly advantegous for Luna if she has Manta Style. Just bear in mind, however, that 
Reflection can be used to turn Moon Glaives against Luna during laning phase.
* Luna very often builds Satanic and Black King Bar, which allows it either to protect herself from Sunder or nullify it's effects.
* Luna can also buy 
Monkey King Bar to help her deal with Terrorblade's high armor, which is a common item on Luna.
Additional:
* If carefully timed, Aghanim's Scepter upgraded Eclipse can quickly finish off Terrorblade before he can get a chance to save himself with Sunder due to its high magical damage if Terrorblade has no Black King Bar available to use.
* Moon Glaives allows Luna to clear Terrorblade's illusions from both, Conjure Image and Manta Style, this can be particularly advantegous for Luna if she has Manta Style. Just bear in mind, however, that Reflection can be used to turn Moon Glaives against Luna during laning phase. Aghanim's Shard upgraded Moon Glaives can be used to reduce damage Luna will take from Terrorblade and his illusions while also clearing waves of them and damaging Terrorblade if he is too close to Luna.
* Luna very often bulds Satanic and Black King Bar as well as it's alternative item Linken's Sphere, which allows her either to protect herself from Sunder or nullify it's effects.
* Luna can also buy Monkey King Bar to help her deal with Terrorblade's high armor, which is a common item on Luna. Likewise Luna can also buy 
Revenant's Brooch or 
Gleipnir whose attacks can also ignore Terrorblade's high armor.
Legion Commander
* Duel's long duration prevents Terrorblade from swapping his health with Sunder.
* Overwhelming Odds deals high damage to Terrorblade's illusions.
Luna
* Heroes that create illusions: Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Luna
* Luna's Moon Glaives combined with Lunar Blessing can easily kill Chen's creeps.
* Eclipse can be used after Luna clears all of Chen's creeps to easily kill Chen or any of his allies before he can save them with 
Hand of God. This can get even worse if Luna buys Aghanim's Scepter. And Chen is not a hero that likes to buy Black King Bar to counter this problem.
Additional:
* Luna's Moon Glaives combined with Lunar Blessing can easily kill Chen's creeps.
* Eclipse can be used after Luna clears all of Chen's creeps to easily kill Chen or any of his allies before he can save them with Hand of God. This can get even worse if Luna buys Aghanim's Scepter. And Chen is not a hero that likes to buy Black King Bar to counter this problem.
Legion Commander
* Chen's fragility and low mobility make him an enticing Duel target.
* Overwhelming Odds and Moment of Courage can take advantage of converted creeps's numbers.
* With enough damage from Duel stacks, Legion Commander can also often kill any of Chen's unfortunate allies before he can use Hand of God.
Additional:
* Chen's frailty and low mobility make him an enticing Duel target.
* Overwhelming Odds and Moment of Courage can take advantage of converted creeps' numbers.
* With enough damage from Duel stacks, Legion Commander can also often kill any of Chen's unfortunate allies before he can use Hand of God.
Legion Commander
* Heroes with abilities that blind or cause Legion Commander to miss will prevent her from winning Duels: Arc Warden, 
Keeper of the Light, Riki, 
Tinker
Luna
* Even though Luna has a hard time laning against Tinker because of 
Heat-Seeking Missile and 
Laser, she can win against him in late game once she buys Black King Bar, as none of Tinker's spells can bypass spell immunity.
* Lucent Beam and 0.25 Eclipse Lucent Mini-stun talent for Eclipse can be used to cancel 
Rearm and prevent Tinker's escape attempts with 
Boots of Travel. Luna can also use Lucent Beam and Eclipse if she is blinded with Laser.
* An ill-timed and ill-positioned 
Blink Dagger will make Tinker a very easy target for Luna's Eclipse that can quickly tear him to shreds. This can get even better if Luna buys Aghanim's Scepter and combines it with 0.25 Eclipse Lucent Mini-stun talent for Eclipse.
* However, Luna needs to approach Tinker carefully, as Tinker is a natural 
Scythe of Vyse wielder, and if he gets a jump on Luna first, he will be able to use it to disable and burst down Luna before she can use Black King Bar, Lucent Beam or Eclipse.
Additional:
* Even though Luna has a hard time laning against Tinker because of Heat-Seeking Missile and Laser, she can win against him in late game once she buys Black King Bar, as none of Tinker's spells can bypass spell immunity.
* Lucent Beam and 0.25 Eclipse Lucent Mini-stun talent for Eclipse can be used to cancel Rearm and prevent Tinker's escape attempts with Boots of Travel. Luna can also use Lucent Beam and Eclipse if she is blinded with Laser.
* An ill-timed and ill-positioned Blink Dagger will make Tinker a very easy target for Luna's Eclipse that can quickly tear him to shreds. This can get even better if Luna buys Aghanim's Scepter and combines it with 0.25 Eclipse Lucent Mini-stun talent for Eclipse.
* However, Luna needs to approach Tinker carefully, as Tinker is a natural Scythe of Vyse wielder, and if he gets a jump on Luna first, he will be able to use it to disable and burst down Luna before she can use Black King Bar, Lucent Beam or Eclipse.
Legion Commander
* Press the Attack can dispel Laser's blind while providing great attack speed and health regeneration.
* Once caught in a Duel, Tinker, who completely relies on his spells to be effective, has little chances of survival with his low health pool and armor.
Legion Commander
* Press the Attack dispels Flaming Lasso.
* Batrider is unlikely to win a Duel in any stage of the game.
Luna
* Lucent Beam can be used to harass Muerta in lane.
* Luna's high movement speed can make it difficult for Muerta to hit her with 
Dead Shot and keep her trapped in 
The Calling.
* 
Pierce the Veil will not save Muerta from Luna at all. Instead, it will sentence her to death as it will amplify the magical damage from both, Lucent Beam and Eclipse, potentially turning Muerta's most powerful ability against her. Aghanim's Scepter upgraded Eclipse can also be used to counter-initiate against Muerta.
* Luna can use Aghanim's Shard upgraded Moon Glaives to reduce all the damage Muerta inflicts on Luna while also damaging Muerta if she is too close to Luna. Bear in mind, however, Aghanim's Shard upgraded Moon Glaives cannot damage Muerta while she is under effects of Pierce the Veil.
* As Luna naturally buys Black King Bar, she will be able to defend herself from Muerta's abilities. Luna can also buy Revenant's Brooch to attack Muerta even through Pierce the Veil.
* Overall, most of the attempts for Muerta to gank and kill Luna will hurt Muerta more than Luna.
Additional:
* Lucent Beam can be used to harass Muerta in lane.
* Luna's high movement speed can make it difficult for Muerta to hit her with Dead Shot and keep her trapped in The Calling.
* Pierce the Veil will not save Muerta from Luna at all. Instead, it will sentence her to death as it will amplify the magical damage from both, Lucent Beam and Eclipse, potentially turning Muerta's most powerful ability against her. Aghanim's Scepter upgraded Eclipse can also be used to counter-initiate against Muerta until Muerta buys Black King Bar.
* Luna can use Aghanim's Shard upgraded Moon Glaives to reduce all the damage Muerta inflicts on Luna while also damaging Muerta if she is too close to Luna. Bear in mind, however, Aghanim's Shard upgraded Moon Glaives cannot damage Muerta while she is under effects of Pierce the Veil as they deal physical damage.
* As Luna naturally buys Black King Bar, she will be able to defend herself from Muerta's abilities. Luna can also buy Revenant's Brooch to attack Muerta even through Pierce the Veil.
* Overall, most of the attempts for Muerta to gank and kill Luna will hurt Muerta more than Luna.
Luna
* Lucent Beam and Eclipse with ministun talent can be used to cancel Requiem of Souls if Shadow Fiend does not have Black King Bar. Likewise, since Shadow Fiend is prone to buying Blink Dagger, an ill-timed Blink Dagger can give Luna a free chance to counter-initiate with Eclipse.
* Moon Glaives and Lunar Blessing allow Luna to outfarm Shadow Fiend in lane and the high physical damage output they provide her can also help her deal with Shadow Fiend even when he buys Black King Bar in late game.
* A well timed Eclipse will burst and kill Shadow Fiend before he even either initiates or gets a chance to retaliate, especially when equipped with Aghanim's Scepter and Ethereal Blade, this could become even worse for Shadow Fiend if he does not have Black King Bar. But bear in mind however, that smart and skilled Shadow Fiend can buy Wind Waker to counter this issue.
* Even though Shadow Fiend can evade all of Luna's abilities with 
Shadow Blade, smart Luna will always buy Dust of Appearance to provide vision on Shadow Fiend to her and her team.
Additional:
* Lucent Beam and Eclipse with ministun talent can be used to cancel Requiem of Souls if Shadow Fiend does not have Black King Bar. Likewise, since Shadow Fiend is prone to buying Blink Dagger, an ill-timed Blink Dagger can give Luna a free chance to counter-initiate with Eclipse.
* Moon Glaives and Lunar Blessing allow Luna to outfarm Shadow Fiend in lane and the high physical damage output they provide her can also help her deal with Shadow Fiend even when he buys Black King Bar in late game.
* A well timed Eclipse will burst and kill Shadow Fiend before he even either initiates or gets a chance to retaliate, especially when equipped with Aghanim's Scepter and Ethereal Blade, this could become even worse for Shadow Fiend if he does not have Black King Bar. But bear in mind however, that smart and skilled Shadow Fiend can buy Wind Waker to counter this issue.
* Even though Shadow Fiend can evade all of Luna's abilities with Shadow Blade, a smart Luna will always buy Dust of Appearance to provide vision on Shadow Fiend to her and her team.
Luna
* If Luna can use Eclipse in anticipation, Magnus will be killed before he can even manages to cast 
Reverse Polarity.
* Aghanim's Scepter upgraded Eclipse is a very good counter-initiation tool against Magnus when he casts Reverse Polarity, granted as long as Luna can cast it from safe distance.
Luna
* If Luna chooses to use Eclipse in anticipation right before Spirit Breaker gets to her with Charge of Darkness, she will be able to kill Spirit Breaker before he will be able to kill her as Spirit Breaker's attack speed is rather low.
* Meanwhile, when Spirit Breaker is focusing on any of Luna's allies with Charge of Darkness, Aghanim's Scepter upgraded Eclipse can be used to counter-initate against Spirit Breaker.
* Aghanim's Shard upgraded Moon Glaives allows Luna to reduce damage from Greater Bash and Nether Strike inflicts on her, and damage Spirit Breaker whenever he is close to her, even while he is invisible.
* Lucent Beam can be used to cancel Spirit Breaker's Charge of Darkness under the condition that Luna is able to cast it on time. Lucent Beam can also be used to cancel Nether Strike. But bear in mind, however, that Spirit Breaker can counter this with 
Planar Pocket from Aghanim's Shard which can be used to reflect Lucent Beam back at Luna.
* If Luna buys Linken's Sphere, it will become nearly impossible for Spirit Breaker to reach Luna unless some of Spirit Breaker's allies can pop it and put it on a cooldown.
* Even though Spirit Breaker can evade all of Luna's abilities with Shadow Blade, smart Luna will always buy Dust of Appearance to provide vision on Spirit Breaker to her and her team. Luna can also buy Gleipnir to counter Spirit Breaker's Charge of Darkness and Shadow Blade combo.
Additional:
* If Luna chooses to use Eclipse in anticipation right before Spirit Breaker gets to her with Charge of Darkness, she will be able to kill Spirit Breaker before he will be able to kill her as Spirit Breaker's attack speed is rather low.
* Meanwhile, when Spirit Breaker is focusing on any of Luna's allies with Charge of Darkness, Aghanim's Scepter upgraded Eclipse can be used to counter-initate against Spirit Breaker.
* Aghanim's Shard upgraded Moon Glaives allows Luna to reduce damage from Greater Bash and Nether Strike inflicts on her, and damage Spirit Breaker whenever he is close to her, even while he is invisible.
* Lucent Beam can be used to cancel Spirit Breaker's Charge of Darkness under the condition that Luna is able to cast it on time. Lucent Beam can also be used to cancel Nether Strike. But bear in mind, however, that Spirit Breaker can counter this with Planar Pocket from Aghanim's Shard which can be used to reflect Lucent Beam back at Luna.
* If Luna buys Linken's Sphere, it will become nearly impossible for Spirit Breaker to reach Luna unless some of Spirit Breaker's allies can pop it and put it on a cooldown.
* Even though Spirit Breaker can evade all of Luna's abilities with Shadow Blade, smart Luna will always buy Dust of Appearance to provide vision on Spirit Breaker to her and her team. Luna can also buy Gleipnir to counter Spirit Breaker's Charge of Darkness and Shadow Blade combo.
Legion Commander
* 
Searing Arrows and Clinkz physical damage items are almost suicidal when used on Legion Commander, as it invites an instant Duel and Legion Commander herself is a natural Blade Mail carrier.
* Duel locks down Clinkz for a long duration, preventing him from escaping with 
Skeleton Walk.
Luna
* Luna's Moon Glaives will not trigger 
Retaliate if they hit some other target first. Also Luna commonly buys items that provide lifesteal such as Satanic, which lets her heal from the damage of Retaliate, meaning that Retaliate has little effect against her.
* Eclipse can be used to counter-initiate against Centaur Warrunner after he jumps in with Blink Dagger, and initiates with 
Hoof Stomp. But remember that Centaur Warrunner can resolve this problem by buying 
Hood of Defiance and it's upgrade 
Pipe of Insight to diminish its damage. Or Blade Mail to reflect the damage of the Eclipse back at Luna.
* Luna also commonly buys Black King Bar, which will allow her to protect herself from both, Centaur Warrunner's abilities (except for the Retaliate), and damage reflect from Blade Mail.
Additional:
* Luna's Moon Glaives will not trigger Retaliate if they hit some other target first. Also Luna commonly buys items that provide lifesteal such as Satanic, which lets her heal from the damage of Retaliate, meaning that Retaliate has limited effect against her.
* Eclipse can be used to counter-initiate against Centaur Warrunner after he jumps in with Blink Dagger, and initiates with Hoof Stomp. But remember that Centaur Warrunner can resolve this problem by buying Hood of Defiance and it's upgrade Pipe of Insight to diminish its damage. Or Blade Mail to reflect the damage of the Eclipse back at Luna.
* Luna also commonly buys Black King Bar, which will allow her to protect herself from both, Centaur Warrunner's abilities (except for the Retaliate), and damage reflect from Blade Mail.
Luna
* Luna's Moon Glaives and Lunar Blessing can help her destroy Tombstone easily, and this becomes more effective if Luna is equipped with Manta Style.
* Spell Immunity of Zombies from Tombstone is a total disadvantage against Luna because Eclipse will strike only Undying, which can turn Undying's own ability against him.
* Though Undying often builds Blade Mail which can turn Luna's burst damage against her, Luna often builds Black King Bar which will allow her to attack Undying freely because Blade Mail cannot pierce spell immunity.
Additional:
* Luna's Moon Glaives and Lunar Blessing can help her destroy Tombstone easily, and this becomes more effective if Luna is equipped with Manta Style.
* Spell Immunity of Zombies from Tombstone is a total disadvantage against Luna because Eclipse will strike only Undying, which can turn Undying's own ability against him.
* Though Undying often builds Blade Mail which can turn Luna's burst damage against her, Luna often builds Black King Bar which will allow her to attack Undying freely because Blade Mail cannot pierce spell immunity.
Legion Commander
* 
Tethered heroes are much harder for Legion Commander to kill in Duels.
* 
Relocate can cancel Duels and save allies.
Luna
* Lucent Beam can be used to cancel both, Tether and Relocate.
* Like with Leshrac's 
Diabolic Edict, 
Lightning Storm and 
Pulse Nova abilities. Luna's Moon Glaives and Eclipse abilities can make short work of Io and its tethered ally, particularly when upgraded with Aghanim's Scepter.
Additional:
* Lucent Beam and 0.25s Eclipse Lucent Ministun talent for Eclipse can be used to cancel both, Tether and Relocate.
* Luna's Moon Glaives and Eclipse abilities can make short work of Io and its tethered ally, particularly when upgraded with Aghanim's Scepter.
Legion Commander
* Duel is very effective against Io due to its low health and armor.
Legion Commander
* Overwhelming Odds's damage stacks with each enemy unit in its radius. If this hits Broodmother and a large number of spiders it can deal significant amounts of damage.
* Moment of Courage has a high chance to proc if Broodmother and all of her spiders are attacking her.
* Duel can keep Broodmother in place long enough for Legion's team to kill her.
Additional:
* Overwhelming Odds is great at killing many stacked up spiderlings, thus giving Legion Commander a large buff.
* Duel is a reliable way to lock down Broodmother, preventing her from running into the treeline.
Luna
* Although Lifestealer can avoid Eclipse with Rage and Infest, Luna's physical damage can be enough to deal with him.
* Manta Style is a common pick on Luna, which can help her dispel slows from 
Ghoul Frenzy and 
Open Wounds. In addition, Lifestealer is not good against illusions created by Manta Style.
Additional:
* Although Lifestealer can avoid Eclipse with Rage and Infest, Luna's physical damage from Moon Glaives and Lunar Blessing can be enough to deal with him.
* Manta Style is a common pick on Luna, which can help her dispel slows from Ghoul Frenzy and Open Wounds. In addition, Lifestealer is not good against illusions created by Manta Style.
* Even though Aghanim's Scepter upgraded Infest can disarm Luna and allow Lifestealer to attack her from inside even if she is spell immune, Luna can easily counter this with Linken's Sphere, which is a common item on Luna.
Luna
* All assassin-type carries in a one against one situation: Meepo, Phantom Assassin, Riki, Ursa. Luna's only chances are that she buys Ethereal Blade or Black King Bar to gain a slight edge against them, or both items if necessary.
Legion Commander
* Heroes with abilities that blind or cause Legion Commander to miss will prevent her from winning Duels: Arc Warden, Keeper of the Light, Riki, Tinker
Luna
* Luna can push very fast with Moon Glaives, which is something Riki cannot deal with well.
* Luna is naturally very fast, making it hard for Riki to trap her in Smoke Cloud.
* Even though Riki can evade Eclipse with his invisibility, smart Luna will always buy Dust of Appearance, providing vision on Riki to her allies and herself.
Additional:
* Luna can push very fast with Moon Glaives, which is something Riki cannot deal with well.
* Luna is naturally very fast, making it hard for Riki to trap her in Smoke Cloud.
* Even though Riki can evade Eclipse with his invisibility, smart Luna will always buy Dust of Appearance, providing vision on Riki to her allies and herself.
Legion Commander
* Another great threat to Riki since her Duel forces him to fight from the front and expose him for the entire duration, almost always guaranteeing an easy win (unless Riki has allies helping him).
* Moment of Courage can become hard to deal with as it doesn't cease with silence.
Legion Commander
* Heroes with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, Lich, Techies, Rubick
Luna
* Moon Glaives can ignore certain abilities that either trigger on attack or give evasion under the condition that the heroes who have them are not primary targets. Examples include: Centaur Warrunner, Windranger, Phantom Assassin, Hoodwink etc.
Luna
* Heroes who are melee but cannot fight back against Eclipse will really struggle with Luna: 
Monkey King, 
Alchemist, 
Timbersaw.
Luna
* Heroes that create illusions: Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Luna
* Illusions and summons are double-edge sword type of matchup for Luna. On one hand, they can tank damage from Eclipse, but on the other hand, she can easily clear them before Eclipse with Moon Glaives. Examples include Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden).
Legion Commander
* Heroes with strong area damage to destroy Phantasm illusions: Axe, 
Ember Spirit, Legion Commander, Phoenix
Legion Commander
* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: 
Venomancer, 
Earth Spirit, 
Ogre Magi
Additional:
* Press the Attack dispels Venomous Gale and Poison Sting from Legion Commander or her teammates.
* Venomancer is an ideal target for Duel due to his lack of mobility and low starting health.
Legion Commander
* Heroes with long or multiple disables will prevent Legion Commander from winning Duels: Shadow Shaman, Lion
Luna
* Luna can easily cancel channeling spells with Lucent Beam and 0.25s Eclipse Lucent Ministun talent for Eclipse, she can also buy Abyssal Blade in case they decide to buy Black King Bar: Enigma's Black Hole, Witch Doctor's Death Ward, Shadow Shaman's Shackles, Lion's Mana Drain, Bane's Fiend's Grip, Pudge's Dismember, Crystal Maiden's Freezing Field, Pugna's Life Drain, Dawnbreaker's Solar Guardian, and Naga Siren's Reel In from Aghanim's Scepter.
Legion Commander
* Lion is extremely dependent on his abilities. Silences like 
Silencer's 
Last Word, magic resistance like Oracle's Fate's Edict, and dispels like Legion Commander's Press the Attack all make his abilities less effective.
Luna
* Even with Black King Bar, Pudge's 
Meat Hook and Dismember can still disable Luna for a fairly long time.
* Many stacks of 
Flesh Heap will make it difficult for Luna to burst down Pudge with Eclipse. Aghanim's Shard upgraded Dismember can also allow Pudge to save an allied hero from being killed by Eclipse.
* Bear in mind, however, that Luna can cancel Dismember if some of her allies are targets. Which may force Pudge to buy Black King Bar earlier.
Luna
* Luna can easily cancel channeling spells with Lucent Beam and 0.25s Eclipse Lucent Ministun talent for Eclipse, she can also buy Abyssal Blade in case they decide to buy Black King Bar: Enigma's Black Hole, Witch Doctor's Death Ward, Shadow Shaman's Shackles, Lion's Mana Drain, Bane's Fiend's Grip, Pudge's Dismember, Crystal Maiden's Freezing Field, Pugna's Life Drain, Dawnbreaker's Solar Guardian, and Naga Siren's Reel In from Aghanim's Scepter.
Legion Commander
* Legion Commander can use Press the Attack on an ally to dispel Dismember. The bonus health regeneration also partially counters the damage of Rot
* Duel can be used on Pudge whilst Rot is active, disabling toggling which may result in a lethal health drain that leaves Legion Commander with a successful duel.
Luna
* Heroes who are melee but cannot fight back against Eclipse will really struggle with Luna: Monkey King, Alchemist, Timbersaw.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: 
Lycan, Arc Warden, 
Warlock, Chen
Legion Commander
* Carries that can out damage Huskar will do well against him: Legion Commander, Faceless Void, Troll Warlord, Phantom Assassin.
Additional:
* Life Break is almost suicidal when used on Legion Commander, as it invites an instant Duel and Legion Commander herself is a natural Blade Mail carrier.
* Huskar's low survivability and mostly on low health make him particularly vulnerable to Legion Commander's high physical damage.
Legion Commander
* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: Venomancer, Earth Spirit, Ogre Magi
Legion Commander
* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: Venomancer, Earth Spirit, Ogre Magi
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen
Legion Commander
* Special mention to Legion Commander, as she can lock down Void Spirit for a long amount of time without worrying too much about being killed by him during the Duel.
Legion Commander
* Bane has powerful single-target abilities that can help his allies win Duels, or at least cripple Legion Commander for the duration.
* Nightmare can waste Duel's entire duration as the dueled units transfer the Nightmare back and forth. This may be prevented if a non-Dueling unit attacks the Nightmared Dueler.
Additional:
* 
Enfeeble, 
Nightmare and Fiend's Grip all prevent Legion Commander from winning Duels, especially when Bane has Blink Dagger.
Luna
* Though Bane's Enfeeble can weaken Luna's physical damage output, it still does not weaken her magical damage output, although it will still reduce her cast range.
* Without Black King Bar, Luna's Lucent Beam and 0.25 Eclipse Mini-stun talent for Eclipse can be used to disable Bane while he is channeling Fiend's Grip.
* Aghanim's Scepter upgraded Eclipse combined with 0.25 Eclipse Mini-stun can repetively stun Bane, and can even discourage him from even trying to use Fiend's Grip.
Additional:
* Though Bane's Enfeeble can weaken Luna's physical damage output, it still does not weaken her magical damage output (although it can still disable her cast range).
* Without Black King Bar, Luna's Lucent Beam and 0.25 Eclipse Mini-stun talent for Eclipse can be used to disable Bane while he is channeling Fiend's Grip.
* Aghanim's Scepter upgraded Eclipse combined with 0.25 Eclipse Mini-stun can repetively stun Bane, and can even discourage him from even trying to use Fiend's Grip.
* Smart and skilled Luna can buy Abyssal Blade to cancel Fiend's Grip even through Black King Bar in case of emergency. Forcing Bane to buy Linken's Sphere.
Legion Commander
* Heroes with strong dispels can dispel Bane's disables from their allies: Oracle, Legion Commander, Omniknight.
Legion Commander
* Heroes that can disable or silence Silencer for a long time, such as Bane and Legion Commander, can lock down Silencer while their allies put him down.
Legion Commander
* Long lockdown is a great way to deal with Axe to prevent Berserker's Call from being used, heroes such as Legion Commander, 
Beastmaster and 
Primal Beast are good examples of this.
Legion Commander
* Heroes with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, Lich, Techies, Rubick
Luna
* A couple of long-range heroes with excellent laning like 
Mirana, 
Lina, 
Necrophos, 
Death Prophet. The key to success is sticking together and attacking Luna whenever she enters the range, without even giving Luna a chance to retaliate. Multiple long-range heroes is a reason to pick another hero.
Legion Commander
* Heroes that cannot move in fights such as a Dueling Legion Commander or anyone channeling a spell like Bane, Pudge, or Enigma are easy Sacred Arrow targets.
Luna
* Even though Luna is the kind of hero that Mirana can handle due to 
Moonlight Shadow rendering her safe from Eclipse with Moonlight Shadow, smart Luna can buy Dust of Appearance, allowing her to provide vision on her to her team, and possibly, kill Mirana.
* Luna's high movement speed allows her to evade 
Sacred Arrow, giving Mirana difficulties in hitting her with it.
* Aghanim's Scepter upgraded Eclipse combined with Dust of Appearance allows Luna to cast it on a hero that is struck by Sacred Arrow and/or after Mirana jumps in with 
Leap.
Additional:
* Even though Luna is the kind of hero that Mirana can handle due to Moonlight Shadow rendering her safe from Eclipse with Moonlight Shadow, smart Luna can buy Dust of Appearance, allowing her to provide vision on her to her team, and possibly, kill Mirana.
* Luna's high movement speed allows her to evade Sacred Arrow, giving Mirana difficulties in hitting her with it.
* Aghanim's Scepter upgraded Eclipse combined with Dust of Appearance allows Luna to cast it on a hero that is struck by Sacred Arrow and/or after Mirana jumps in with Leap.
Legion Commander
* Heroes that can protect or dispel stunned allies such as Legion Commander, Outworld Destroyer, Shadow Demon and Oracle can reduce the effectiveness of Sacred Arrow.
Luna
* Heroes that create illusions: Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Luna
* Enchantress has pitiful HP, even more pitiful than Luna, so Lucent Beam and Eclipse will often harass and/or kill her through her Untouchable.
* With Moon Glaives, Luna can clear Enchantress's creep wave efficiently.
Additional:
* Though Enchantress's 
Untouchable can greatly reduce Luna's attack speed, and can go through any form of Spell Immunity, she has a pitiful HP so Lucent Beam and Eclipse can kill her very quickly.
* Moon Glaives allows Luna to clear Enchantress's creeps very efficiently.
Luna
* Heroes that create illusions: Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Legion Commander
* Heroes with global abilities can give Legion Commander's opponent an edge in Duels from anywhere on the map: Nature's Prophet, Ancient Apparition, Zeus, Invoker, Treant Protector
Luna
* Moon Glaives and Lunar Blessing help Luna quickly kill Nature's Prophet's treants.
* Luna can easily cancel Teleportation with her Lucent Beam.
* Even though Nature's Prophet can evade all of Luna's abilities with Shadow Blade, a smart Luna will always buy Dust of Appearance to provide vision on Shadow Fiend to her and her team.
Additional:
* Moon Glaives and Lunar Blessing help Luna quickly kill Nature's Prophet's treants. Aghanim's Shard upgraded Moon Glaives can also reduce damage Nature's Prophet will inflict on Luna while they are active.
* Luna can easily cancel Teleportation with her Lucent Beam.
* Even though Nature's Prophet can evade all of Luna's abilities with Shadow Blade, a smart Luna will always buy Dust of Appearance to provide vision on Nature's Prophet to her and her team.
Legion Commander
* Legion Commander's Overwhelming Odds deals damage for every Treant it hits, which allows it to easily wipe out large waves of them.
Luna
* Heroes that outrange Luna can be a problem for her: Drow Ranger, Sniper.
Legion Commander
* Sniper's low mobility and lack of defensive abilities make him an easy gank target for the entire game, especially if Blink Dagger is picked up.
Luna
* Heroes with damage-over-time abilities easily allow Bristleback to turn his back in order to proc 
Bristleback continuously and to massively reduce to damage dealt to him: Arc Warden, Venomancer, Luna.
Additional:
* 
Quill Spray and Bristleback harass Luna more efficiently than she does with Lucent Beam.
* Bristleback helps return a lot of damage to Luna’s team if she uses her nukes on him and he has his back to her, and her only way to counter this is by buying Silver Edge.
* 
Viscous Nasal Goo and 
Warpath are enough to outrun a speedy Luna.
* Bristleback tends to be a frequent carrier of 
Crimson Guard and 
Eternal Shroud, which are good protection from Moon Glaives and Eclipse.
* For the same reasons, Bristleback makes a very powerful ally for Luna when they are in the same team.
Legion Commander
* Duel makes Bristleback fight Legion Commander face to face, forcing him to take full damage.
* Press the Attack dispels the slow from stacks of Viscous Nasal Goo.
Additional:
* When dueled, Bristleback will have to face Legion head on, not allowing his passive Bristleback to come into effect.
Luna
* Escape-type carries: Slark, Storm Spirit, Weaver.
Legion Commander
* Duel's long duration prevents Weaver from activating Time Lapse or escaping with 
Shukuchi.
Luna
* A couple of long-range heroes with excellent laning like Mirana, Lina, Necrophos, Death Prophet. The key to success is sticking together and attacking Luna whenever she enters the range, without even giving Luna a chance to retaliate. Multiple long-range heroes is a reason to pick another hero.
Legion Commander
* Duel is a great initiation to kill Death Prophet before she can cast Exorcism. Furthermore, Legion Commander often builds Blade Mail and can reflect Exorcism's damage to kill Death Prophet easily.
Legion Commander
* Heroes with abilities that blind or cause Legion Commander to miss will prevent her from winning Duels: Arc Warden, Keeper of the Light, Riki, Tinker
Legion Commander
* Press the Attack can dispel Blinding Light or Solar Bind from a hero.
* Duel can be used to instantly take Keeper of the Light out of a team-fight.
Legion Commander
* 
Wraith King's 
Reincarnation allows him to severely punish Legion Commander after he revives, as her abilities are on cooldown. Legion Commander is still awarded a Duel win if Wraith King reincarnates.
Additional:
* Wraith King makes a poor Duel target, as he can be already quite hard to bring down once, and then you have to worry about his second life.
* However, even if Legion Commander does win the duel when Reincarnation is off cooldown, she still receives the permanent victory damage bonus because taking down Wraith King's first life still counts as a "kill".
Luna
* Even though Wraith King can easily get a chance to retaliate with Reincarnation after Luna uses Eclipse against him, smart Luna can also turn Reincarnation against him by using Eclipse right after Reincarnation triggers and gets on cooldown, giving Luna an element of surprise she can use against Wraith King.
* Moon Glaives can be used to clear the waves of Wraith King's skeleton warriors summoned from 
Vampiric Spirit.
Additional:
* Even though Wraith King can easily get a chance to retaliate with Reincarnation after Luna uses Eclipse against him, smart Luna can also turn Reincarnation against him by using Eclipse right after Reincarnation triggers and gets on cooldown, giving Luna an element of surprise she can use against Wraith King.
* Moon Glaives can be used to clear the waves of Wraith King's skeleton warriors summoned from Vampiric Spirit.
Luna
* A couple of long-range heroes with excellent laning like Mirana, Lina, Necrophos, Death Prophet. The key to success is sticking together and attacking Luna whenever she enters the range, without even giving Luna a chance to retaliate. Multiple long-range heroes is a reason to pick another hero.
Luna
* Even though Luna has a hard time laning against Necrophos, his 
Ghost Shroud won’t protect him in teamfights because it will increase the damage from Lucent Beam and Eclipse.
* Luna is a natural Black King Bar wielder, and none of Necrophos's spells can bypass spell immunity outside of 
Heartstopper Aura.
Additional:
* Even though Luna has a hard time laning against Necrophos, his Ghost Shroud won’t protect him in teamfights because it will increase the damage from Lucent Beam and Eclipse.
* Luna is a natural Black King Bar wielder, and none of Necrophos's spells can bypass spell immunity outside of Heartstopper Aura.
Luna
* All assassin-type carries in a one against one situation: Meepo, Phantom Assassin, Riki, Ursa. Luna's only chances are that she buys Ethereal Blade or Black King Bar to gain a slight edge against them, or both items if necessary.
Luna
* Even though Phantom Assassin can easily kill Luna in few strikes, Luna can also do the same to Phantom Assassin if she is not careful.
* An ill-timed and ill-positioned 
Phantom Strike will make Phantom Assassin an easy target for counter-attack with Eclipse if she does not have Black King Bar available to use and if Phantom Assassin cannot kill Luna fast enough. This can be even better if Luna buys Aghanim's Scepter.
* Moon Glaives can ignore 
Blur's evasion if Luna attacks an enemy near Phantom Assassin.
* Luna can counter Blur's evasion by buying either Silver Edge, or Monkey King Bar, which are common items on Luna.
* Luna just has to be careful about 
Fan of Knives from Aghanim's Shard and 
Coup De Grace, as Fan of Knives can disable Moon Glaives and Lunar Blessing while Coup De Grace can deal serious damage to her even if she is spell immune, though this issue can be solved by buying Ethereal Blade, which is a situational item on Luna.
Additional:
* Even though Phantom Assassin can easily kill Luna in few strikes, Luna can also do the same to Phantom Assassin if she is not careful.
* An ill-timed and ill-positioned Phantom Strike will make Phantom Assassin an easy target for counter-attack with Eclipse if she does not have Black King Bar available to use and if Phantom Assassin cannot kill Luna fast enough. This can be even worse if Luna buys Aghanim's Scepter.
* Moon Glaives can ignore Blur's evasion if Luna attacks an enemy near Phantom Assassin. Aghanim's Shard upgraded Moon Glaives can also reduce damage from Coup De Grace and Moon Glaives Phantom Assassin inflicts on Luna and damage Spirit Phantom Assassin she is close to her. And the Aghanim's Shard upgraded Moon Glaives have true strike for their duration, which renders Blur's evasion insignificant.
* Luna can counter Blur's evasion by buying either Silver Edge, or Monkey King Bar, which are common items on Luna.
* Luna just has to be careful about Fan of Knives from Aghanim's Shard and Coup De Grace, as Fan of Knives can deal health-based damage to Luna and disable Moon Glaives and Lunar Blessing while Coup De Grace can deal serious damage to her even if she is spell immune, though this issue can be partially solved by buying Ethereal Blade, which is a situational item on Luna.
Luna
* Every hero that can withstand or prevent Eclipse at level 7: Juggernaut, Riki, Clockwerk, Drow Ranger, Abaddon, Faceless Void, Weaver, Outworld Destroyer.
Legion Commander
* Drow Ranger's low mobility and lack of defensive abilities make her an easy gank target in the early to mid-game.
* A Dueling Drow Ranger will lose her precious 
Marksmanship, reduce her damage output significantly, and will more likely lose that Duel.
Luna
* Heroes that rely on base damage: Luna, Phantom Lancer are easily countered with Anchor Smash.
Luna
* Luna often builds Black King Bar, and none of Tidehunter's spells can bypass spell immunity.
* Though 
Anchor Smash can weaken Luna's physical damage, it does not weaken her magical damage, which means that Lucent Beam and Eclipse deal a lot of magic damage in the early and mid-game, which can bypass Tidehunter's Kraken Shell.
Additional:
* Luna often builds Black King Bar, and none of Tidehunter's spells can bypass spell immunity.
* Though Anchor Smash can weaken Luna's physical damage, it does not weaken her magical damage, which means that Lucent Beam and Eclipse deal a lot of magic damage in the early and mid-game, which can bypass Tidehunter's Kraken Shell.
Legion Commander
* Enigma can be a perfect counter-initiator with his ultimate. A perfectly timed Black Hole will turn the tide of any initiation, especially from heroes like; 
Spirit Breaker, Legion Commander, Axe, 
Puck, and 
Slardar.
Luna
* Without Black King Bar, Luna will be able to cancel Enigma's Black Hole from safe distance with her Lucent Beam or with 0.25s Eclipse Lucent Ministun talent for Eclipse and counter-initiate with Eclipse. This can get even worse for Enigma once Luna gets Aghanim's Scepter and combines it with 0.25s Eclipse Lucent Ministun talent that will allow Luna to use Eclipse from safe distance.
* If Luna chooses to use Eclipse in anticipation right after Enigma jumps in with Blink Dagger, she will be able to kill Enigma before he even gets a chance to use Black Hole. Aghanim's Scepter upgraded Eclipse can be used to counter-initiate against Enigma from safe distance if he has no Black King Bar available to use.
* Luna commonly buys Satanic, which can help her recover from Enigma's Black Hole in case she survives it.
* Moon Glaives combined with Lunar Blessing can make a short work of Enigma's Eidolons before Luna uses Eclipse. Aghanim's Shard upgraded Moon Glaives can be used to reduce damage Luna will take from Enigma's Eidolons and Black Hole if used in anticipation while also clearing waves of Enigma's Eidolons and damaging Enigma if he is too close to Luna.
* Bear in mind, however, that once Enigma gets Black King Bar, Luna will be out of solutions to cancel Black Hole, and going for Abyssal Blade on Luna can be risky due to Abyssal Blade's very short cast range.
Additional:
* Without Black King Bar, Luna will be able to cancel Enigma's Black Hole from safe distance with her Lucent Beam or with 0.25s Eclipse Lucent Ministun talent and counter-initiate with Eclipse. This can get even worse for Enigma once Luna gets Aghanim's Scepter and combines it with 0.25s Eclipse Lucent Ministun talent that will allow Luna to use Eclipse from safe distance.
* If Luna chooses to use Eclipse in anticipation right after Enigma jumps in with Blink Dagger, she will be able to kill Enigma before he even gets a chance to use Black Hole.
* Luna commonly buys Satanic, which can help her recover from Enigma's Black Hole in case she survives it.
* Moon Glaives combined with Lunar Blessing can make a short work of Enigma's Eidolons before Luna uses Eclipse.
* Bear in mind, however, that once Enigma gets Black King Bar, Luna will be out of solutions to cancel Black Hole, and going for Abyssal Blade on Luna can be risky due to Abyssal Blade's very short cast range.
Luna
* A couple of nukers and disablers on the same lane can finish a squishy Luna efficiently despite a teammate's assistance: Sven + Shadow Shaman.
Legion Commander
* Heroes with long or multiple disables will prevent Legion Commander from winning Duels: Shadow Shaman, Lion
Luna
* Luna's high magical damage burst from Lucent Beam and Eclipse can take advantage of Shadow Shaman's low health and strength gain.
* Without Black King Bar, Luna's Lucent Beam and 0.25 Eclipse Mini-stun talent for Eclipse can be used to disable Shadow Shaman while he is channeling Shackles.
* Aghanim's Scepter upgraded Eclipse combined with 0.25 Eclipse Mini-stun can repetively stun Shadow Shaman, and can even discourage him from even trying to use Shackles.
* Luna is a natural Black King Bar wielder, and almost none of Shadow Shaman's spells can bypass spell immunity, except for 
Mass Serpent Ward.
* Bear in mind, however, that if Shadow Shaman gets a jump on Luna first, he will be able to use 
Hex to disable Luna and burst her down before she can use Black King Bar, Lucent Beam or Eclipse. In addition, Moon Glaives cannot bounce on Mass Serpent Wards at all.
Additional:
* Luna's high magical damage burst from Lucent Beam and Eclipse can take advantage of Shadow Shaman's low health and strength gain.
* Without Black King Bar, Luna's Lucent Beam and 0.25 Eclipse Mini-stun talent for Eclipse can be used to disable Shadow Shaman while he is channeling Shackles.
* Aghanim's Scepter upgraded Eclipse combined with 0.25 Eclipse Mini-stun can repetitively stun Shadow Shaman, and can even discourage him from even trying to use Shackles.
* Luna is a natural Black King Bar wielder, and almost none of Shadow Shaman's spells can bypass spell immunity, except for Mass Serpent Ward.
* Bear in mind, however, that if Shadow Shaman gets a jump on Luna first, he will be able to use Hex to disable Luna and burst her down before she can use Black King Bar, Lucent Beam or Eclipse. In addition, Moon Glaives cannot bounce on Mass Serpent Wards at all.
Legion Commander
* Pudge, Legion Commander and Axe will make the match a living hell for Shadow Shaman, since they are known for surprise attacks from the fog and quickly killing low HP heroes. They can also interrupt Shadow Shaman's channeling, Legion being especially problematic, as she can use Press the Attack on an ally who is hexed as well.
Luna
* Even though Luna can clear Phantom Lancer's illusions with Moon Glaives, Phantom Lancer can create too many illusions to tank Luna's Eclipse and for Luna to handle overall.
* Doppelganger can be used to dodge a number of Lucent Beams during Eclipse.
* Phantom Lancer can chase Luna effectively regardless of her high movement speed thanks to 
Phantom Rush and 
Spirit Lance.
* Luna's low health pool is easily exploited by the sheer damage output from Phantom Lancer's illusions. Additionally, Phantom Lancer can often create more illusions for Luna to handle.
Luna
* Illusions and summons are double-edge sword type of matchup for Luna. On one hand, they can tank damage from Eclipse, but on the other hand, she can easily clear them before Eclipse with Moon Glaives. Examples include Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden).
Legion Commander
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, Chaos Knight, Terrorblade, Naga Siren
Additional:
* Overwhelming Odds deals high damage to Phantom Lancer's illusions.
* Duel's long duration prevents Phantom Lancer from using Doppelganger.
Legion Commander
* Heroes that lack burst damage will have a difficult time taking down Monkey King, and fare badly against Jingu Mastery: Legion Commander, Lifestealer, Weaver, Wraith King
Luna
* Heroes who are melee but cannot fight back against Eclipse will really struggle with Luna: Monkey King, Alchemist, Timbersaw.
Luna
* Frail heroes who lack mobility can also be an easy target to lock down with Chronosphere, such as Drow Ranger, Luna, Sniper, Terrorblade.
Luna
* Luna's Eclipse can be used for counter-attacks and interception against gap-closing heroes who use their blinking abilities without protection or who recklessly jump on her, provided that Luna is able to cast it in time. Examples include: 
Queen of Pain, Riki, Phantom Assassin, Faceless Void and pretty much any hero who relies on Blink Dagger to close the gap.
Luna
* Heroes that create illusions: Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Legion Commander
* Song of the Siren lasts long enough to prevent a successful Duel (but only if Naga wasn't the target).
Luna
* Luna's Moon Glaives and Lunar Blessing can clear waves of Naga Siren's illusions from Mirror Image.
* Once Naga Siren's illusions are cleared with Aghanim's Shard upgraded Moon Glaives, Eclipse can often finish off Naga Siren before she can escape with 
Song of the Siren.
* A well-timed Aghanim's Scepter upgraded Eclipse combined with 0.25 Eclipse Lucent Ministun talent can be casted at long range and allow Luna to burst down Naga Siren faster and repetively stun Naga Siren, preventing her from escaping with Song of the Siren and 
Town Portal Scroll without getting caught in it's range.
* Luna is a natural Black King Bar wielder unlike Naga Siren who barely goes for it, which allows Luna to freely attack Naga Siren during Song of the Siren and potentially get rid of the most of the damage and crowd-control from Naga Siren.
Additional:
* Luna's Moon Glaives and Lunar Blessing can clear waves of Naga Siren's illusions from Mirror Image, especially when combined with Gleipnir and Manta Style. Aghanim's Shard upgraded Moon Glaives can also be used to destroy Naga Siren's illusions and damage the real Naga Siren if they are too close to Luna while also reducing any damage Naga Siren inflicts on Luna for their duration.
* Once Naga Siren's illusions are cleared, Eclipse can often finish off Naga Siren before she can escape with Song of the Siren.
* A well-timed Aghanim's Scepter upgraded Eclipse combined with 0.25 Eclipse Lucent Ministun talent can be casted at long range and allow Luna to burst down Naga Siren faster and repetively stun Naga Siren, preventing her from escaping with Song of the Siren and Town Portal Scroll without getting caught in it's range.
* Luna is a natural Black King Bar wielder unlike Naga Siren who barely goes for it, which allows Luna to freely attack Naga Siren during Song of the Siren and potentially get rid of the most of the damage and crowd-control from Naga Siren.
Legion Commander
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, Chaos Knight, Terrorblade, Naga Siren
Legion Commander
* 
Decrepify on either hero stops Legion Commander from completing a Duel, and dissuades her from initiating Duels on ethereal allies.
* Life Drain can help Pugna's teammates win a fight, either by killing Legion Commander or replenishing her target's health.
Additional:
* Decrepify prevents Legion Commander from attacking allies during Duel, regardless if it's used on her or on the ally .
* Pugna can easily cast Decrepify, Nether Blast and Life Drain on Legion during the 4/4.75/5.5/8 seconds of duel
Luna
* Luna can deal constant damage to Pugna through the low-cooldown Lucent Beam and her right clicks.
* Life Drain will be always canceled by Lucent Beam if Pugna does not have Black King Bar.
* Decrepify can be suicide against Luna due to Lucent Beam and Eclipse.
* 
Nether Ward is rather weak against Luna because unlike other heroes who rely on magical damage to damage or kill enemies, yet their ablities have very high mana costs, Luna does not have abilities that cost a lot of mana and Luna mostly uses her abilities to initiate a teamfight or to finish off fleeing enemy heroes.
* Luna is a common Black King Bar carrier, which allows her to protect herself against Pugna's only-magical damage output.
Additional:
* Luna can deal constant damage to Pugna through the low-cooldown Lucent Beam and her right clicks.
* Life Drain will be always canceled by Lucent Beam if Pugna does not have Black King Bar.
* Decrepify can be suicide against Luna due to Lucent Beam and Eclipse.
* Nether Ward is rather weak against Luna because unlike other heroes who rely on magical damage to damage or kill enemies, yet have very high mana costs, she does not have abilities that cost a lot of mana and Luna mostly uses her abilities to initiate a teamfight or to finish off fleeing enemy heroes.
* Luna is a common Black King Bar carrier, which allows her to protect herself against Pugna's only-magical damage output.
Legion Commander
* Earthshaker's AoE stuns can save ally against Duel, forcing Legion Commander to spend Aghanim's Scepter or Black King Bar.
Luna
* Luna's Lucent Beams and Eclipse will prevent Earthshaker from initiating or re-initiating.
* Aghanim's Scepter upgraded Eclipse can be used to counter-initiate against Earthshaker after he uses Aghanim's Scepter upgraded 
Enchant Totem.
* Skilled Luna can buy either {I|Gleipnir
Additional:
* Luna's Lucent Beams and Eclipse will prevent Earthshaker from initiating or re-initiating.
* Aghanim's Scepter upgraded Eclipse can be used to counter-initiate against Earthshaker after he uses Aghanim's Scepter upgraded Enchant Totem.
* Skilled Luna can buy either {I|Gleipnir
Legion Commander
* 
Atrophy Aura's percentage-based damage reduction greatly diminishes Legion Commander's overall damage output, even if she has won many Duels
* Legion Commander cannot get out the way of Firestorm because she is stationary.
Additional:
* Atrophy Aura makes it hard for Legion Commander to win Duels.
* 
Fiend's Gate can be used to save Underlord and his allies from a Duel or to intercept Legion Commander, because outside from Overwhelming Odds, Legion Commander has no other area-of-effect abilities.
Luna
* Lunar Blessing gives allies bonus damage and armor required to endure against Atrophy Aura early on.
* Eclipse can be devastating for Underlord's team when they're grouped up for Fiend's Gate, it can also be used to intercept arrivals with Fiend's Gate. And Pit of Malice does not prevent Luna to use it.
* To make things even better, Aghanim's Scepter upgraded Eclipse can finish off Underlord or any of his teammates escape attempts with Fiend's Gate if timed correctly.
Additional:
* Lunar Blessing gives allies bonus damage required to endure against Atrophy Aura in most stages of the game.
* Eclipse can be devastating for Underlord's team when they're grouped up for Fiend's Gate. It can also be used to intercept arrivals with Fiend's Gate. And 
Pit of Malice does not prevent Luna from using it.
* To make things even worse, Aghanim's Scepter upgraded Eclipse can finish off Underlord or any of his teammates escape attempts with Fiend's Gate if timed correctly.
Legion Commander
* 
Purification prevents Legion Commander from killing her target, and will always hit her during Duels.
* 
Guardian Angel completely wastes Duel's duration and can save an ally across the map when upgraded with Aghanim's Scepter.
Additional:
* Both Guardian Angel and Purification are perfect counters against Duel.
Luna
* Guardian Angel does not offer protection from Eclipse, though it will negate damage from Moon Glaives.
* Luna's high magical damage from Lucent Beam and Eclipse can often finish allied heroes before Omniknight can save them with Purification.
* Likewise, Luna's high physical damage from Moon Glaives and Lunar Blessing is strong enough to counter debuff immunity from 
Repel.
Additional:
* Guardian Angel does not offer protection from Eclipse, though it will negate damage from Moon Glaives.
* Luna's high magical damage from Lucent Beam and Eclipse can often finish allied heroes before Omniknight can save them with Purification.
Luna
* Because of her low range, Luna cannot easily destroy 
Healing Ward.
* Both Blade Fury and 
Omnislash are direct counters to Eclipse, offering Juggernaut spell immunity and invulnerabilty. Therefore, Luna will need assistance in taking down Juggernaut as going solo will not be successful.
Legion Commander
* Duel pierces spell immunity and forces him to attack Legion Commander, making him unable to use Omnislash.
Luna
* Heroes that create illusions: Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Luna
* Illusions and summons are double-edge sword type of matchup for Luna. On one hand, they can tank damage from Eclipse, but on the other hand, she can easily clear them before Eclipse with Moon Glaives. Examples include Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden).
Luna
* Heroes that create illusions: Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Legion Commander
* Magnetic Field prevents Legion Commander from getting wins with Duel.
Additional:
* 
Magnetic Field prevents Legion Commander from easily gaining wins with Duel.
Luna
* Luna's Moon Glaives allow her to clear Arc Warden's 
Tempest Double.
* Luna's short range and fast movement speed allow her to fight Arc Warden inside his Magnetic Field.
Additional:
* Luna's Moon Glaives allow her to clear Arc Warden's Tempest Double.
* Luna's short range and fast movement speed allow her to fight Arc Warden inside his Magnetic Field.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen
Legion Commander
* 
Cold Embrace saves allies from dying in Duels.
* 
Winter's Curse turns Legion Commander's high damage against her allies, giving the enemy team little time to react.
* However, Winter Wyvern lanes very poorly against Legion Commander due to Press the Attack removing all the debuffs she can give. Winter Wyvern also has little chances of surviving if she gets Dueled herself.
Additional:
* Cold Embrace is very effective against Duel.
* Also, casting Winter's Curse at Legion Commander while an ally is in a Duel will stun her for most of the duration, possibly preventing lethal damage dealt to your ally. It can also turn her high-damage against her teammate.
Luna
* Cold Embrace is no salvation against Lucent Beam and Eclipse.
* Moon Glaives will not hit a hero affected by Winter's Curse, making it weak against allies, but strong versus enemies.
* Luna has better night vision provided by Lunar Blessing than Winter Wyvern when affected by Arctic Burn.
Additional:
* Cold Embrace is no salvation against Lucent Beam and Eclipse.
* Moon Glaives will not hit a hero affected by Winter's Curse, making it weak against allies, but strong versus enemies.
* Luna has better night vision provided by Lunar Blessing than Winter Wyvern when affected by Arctic Burn.
Luna
* Heroes that create illusions: Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse, but that will require lots of farming for right-click items.
Luna
* Illusions and summons are double-edge sword type of matchup for Luna. On one hand, they can tank damage from Eclipse, but on the other hand, she can easily clear them before Eclipse with Moon Glaives. Examples include Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as Nature's Prophet, Lone Druid, Chen, Enchantress, Meepo and Arc Warden).
Legion Commander
* 
Gravekeeper's Cloak protects Visage from Legion Commander's attacks for most of Duel's duration.
* Chain stuns from Visage's familiars prevents Legion Commander from winning Duels.
Luna
* Moon Glaives is very effective against Visage because not only it can easily destroy Visage's Familiars, but can also remove one instance of Gravekeeper's Cloak upon each hit to Visage, leaving him susceptible to damage.
* Once Visage's Familiars are picked off and all instances of Gravekeeper's Cloak are removed, Luna will be able to easily kill Visage with Eclipse.
Additional:
* Moon Glaives is very effective against Visage because not only it can easily destroy Visage's Familiars, but can also remove one instance of Gravekeeper's Cloak upon each hit to Visage, leaving him susceptible to damage.
* Once Visage's Familiars are picked off and all instances of Gravekeeper's Cloak are removed, Luna will be able to easily kill Visage with Eclipse.
Luna
* Should Luna choose to buy
Manta Style, Medusa will be able to kill illusions from them with 
Split Shot and 
Mjollnir, which is a common item on Medusa.
Mystic Snake allows Medusa to easily harass Luna and steal mana from her, preventing Luna from retaliating with 
Lucent Beam.
Eclipse thanks to 
Mana Shield, which can cause Luna to struggle greatly in bursting down Medusa and force her to buy 
Diffusal Blade and it's upgrade 
Disperser.
Black King Bar, Medusa's 
Stone Gaze will still be able to disable Luna, which could even discourage her from counter-initiating with Eclipse.
Manta Style, Medusa will be able to kill illusions from them with 
Split Shot and 
Mjollnir, which is a common item on Medusa.
Mystic Snake allows Medusa to easily harass Luna and steal mana from her, preventing Luna from retaliating with 
Lucent Beam.
Eclipse thanks to 
Mana Shield, and since Luna is not a hero that often goes for 
Diffusal Blade, she will struggle greatly in bursting down Medusa.
Black King Bar, Medusa's 
Stone Gaze will still be able to disable Luna, which could even discourage her from counter-initiating with Eclipse.
*
* Medusa can survive
* Even with
Additional:
* Should Luna choose to buy
*
* Medusa can survive
* Even with
* For the same reasons, Medusa makes a very powerful ally for Luna when they are in the same team.
Legion Commander
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Mana Shield makes Medusa very hard to take down in Duels.
Stone Gaze stops Legion Commander from Dueling altogether, regardless of who she targets.
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