Lina
* 
Light Strike Array has a long delay, making her vulnerable for Ursa's burst.
* Enrage can protect Ursa against Lina's high magical burst.
Legion Commander
* 
Legion Commander is unlikely to win a 
Duel against Ursa.
Additional:
* 
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
Lina
* Heroes with a lot of burst damage, especially those who rely on casting spells: 
Lina, 
Zeus.
Legion Commander
* 
Mana Shield makes Medusa very hard to take down in Duels.
* 
Stone Gaze stops Legion Commander from Dueling altogether, regardless of who she targets.
Lina
* Heroes who cannot prevent Sven from killing supports will always be at a disadvantage in fights such as Lina, 
Slark and Zeus.
Additional:
* Sven has a high health pool and is a natural 
Black King Bar holder and is very hard to kill for Lina.
* Sven also has high physical damage, making it easy for him to burst her down.
Legion Commander
* Strong laners are usually at a disadvantage because of how well Sven can jungle. Heroes such as 
Dark Seer. 
Underlord and Legion Commander may find that later Sven takes care of them very quickly after some jungle farming.
Additional:
* 
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.
Lina
* Heroes with long animations can be frequently interrupted with Cold Snap: 
Earthshaker, 
Monkey King, 
Shadow Fiend Lina
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
* 
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.
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.
Legion Commander
* 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.
Additional:
* 
Astral Imprisonment prevents Legion Commander from killing her opponents in Duels.
Legion Commander
* Earthshaker's AoE stuns can save ally against Duel, forcing Legion Commander to spend 
Aghanim's Scepter or Black King Bar.
Legion Commander
* 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".
Legion Commander
* Solar Guardian can save allies who are being dueled and will interrupt her Duel initiation.
Lina
* 
Spectral Dagger and 
Haunt allow Spectre to get close to Lina.
* 
Desolate is very strong against Lina, who's usually a bit isolated in fights because of her high attack and cast range.
* 
Dispersion can mitigate a good portion of Lina's burst damage, allowing Spectre to turn on her afterwards.
Additional:
* Spectre can very easily close the distance on Lina with Haunt and Spectral Dagger, and due to Lina's abysmal mobility without a 
Blink Dagger and terrible health pool and armor, Lina easily gets slaughtered due Desolate.
* Dispersion can mitigate a good portion of Lina's burst damage, allowing Spectre to turn against her afterwards.
Legion Commander
* 
Mystic Flare can easily burst down Legion Commander while she is Dueling.
Lina
* 
Time Walk will easily backtrack Lina's burst damage (especially Laguna Blade) if not timed correctly.
* During 
Chronosphere, squishy heroes like Lina will be main target of Faceless Void in his ultimate.
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.
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.
Lina
* 
Rage protects Lifestealer from all of Lina's abilities (except an upgraded Laguna Blade).
* 
Open Wounds is great to keep Lina in place because she has no abilities to help her escape.
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.
Legion Commander
* 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
* 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.
Lina
* Heroes with low mobility that rely on spells: Zeus, Lina, 
Crystal Maiden.
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
Legion Commander
* 
Troll Warlord's melee bash and high attack speed can often help him and his allies win Duels against Legion Commander.
Lina
* Both 
Lion's 
Finger of Death and Lina's 
Laguna Blade have a 0.25 second delay before the damage is dealt.
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.
Lina
* Lina is a common 
Eul's Scepter of Divinity carrier which can waste some duration of Borrowed Time and following up with Laguna Blade if timed correctly.
Lina
* Marci can be effective against vulnerable squishy heroes that cannot deal with heroes that jump onto them - 
Sniper, 
Drow Ranger, Lina, 
Rubick, etc.
Lina
* Heroes with powerful nuke can waste their precious abilites on her Refraction during a ganking attempt or chaos combat: 
Lich, Lina, Sniper, 
Outworld Destroyer Zeus
Lina
* Low health spellcasters: Lina, 
Witch Doctor, 
Tinker, 
Keeper of the Light, all rely heavily on their spells and are fragile heroes. They all also have avoidable spells, allowing Puck to get to them and quickly burst them down.
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
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
* 
Magnetic Field prevents Legion Commander from easily gaining wins with Duel.
Additional:
* Magnetic Field prevents Legion Commander from getting wins with Duel.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: 
Lycan, 
Arc Warden, 
Warlock, 
Chen
Lina
* 
Arcane Curse discourages Lina from using her abilities, preventing her from building up Fiery Soul stacks.
* 
Last Word and 
Global Silence are great against Lina for the same reason, as well as interrupting her combos and preventing her from casting spells.
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
* 
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.
Lina
* Heroes who have channeled abilities can be stunned by Light Strike Array, like Witch Doctor with Death Ward and Bane's 
Fiend's Grip.
Additional:
* Light Strike Array cancels out Death Ward from a long distance.
Lina
* 
Dark Pact can be cast during the cast animation of Light Strike Array and dispel its stun.
* 
Pounce allows Slark to close the gap to Lina.
* 
Shadow Dance prevents Lina from killing Slark with her Laguna Blade when his HP gets low.
Lina
* Heroes with heavy magical nukes will take advantage of Slark's poor HP or force him to use Shadow Dance early: Lina, Lion, Zeus
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.
Lina
* Heavy nukers will do well against Cold Embrace (Lina, Zeus etc).
Lina
* 
Dragon Slave is easy to steal, and provides Rubick with a useful nuke.
* Light Strike Array serves as a cheap nuke as well as a crowd control ability.
* Rubick uses the fixed 0.15 second cast time when casting Light Strike Array, much faster than Lina herself.
* Rubick can gurantee a stun by throwing the victim into the area with 
Telekinesis, extending the overall lockdown duration.
* Laguna Blade is an awesome ultimate that gives huge burst damage.
* 
Arcane Supremacy (combined with Level 25 talent +40% Spell Amp For Stolen Spells, as of 7.31c) increases its damage before reduction to a whopping 660/882/1134(830/1162/1494) (and even more so with Aghanim's Scepter), without considering spell amplification from items.
* Laguna Blade is an intelligence hero with no regen ability, and casting Laguna Blade back to Lina can result in her unexpected sudden death, or severly hinder her presence in the rest of teamfight. Nevertheless, the skill can also be cast on other squishy heroes or help bursting down enemy carries.
* Light Strike Array and Laguna Blade has a short cast range, and Rubick can extend its range thanks to Arcane Supremacy.
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
Lina
* Being a hero with low health and abysmal mobility, Lina can nuke her down easily.
* Since Crystal Maiden's 
Freezing Field is a channeled ability, Lina can use her Light Strike Array to cancel it easily.
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.
Lina
* Laguna Blade is one of the best tools to kill Terrorblade before he can use 
Sunder due to its high magical (pure with Laguna Blade damage is Pure and pierces Spell Immunity talent) burst damage.
* Dragon Slave and Light Strike Array allows Lina to clear Terrorblade's illusions from both, Conjure Image and 
Manta Style.
Additional:
* Laguna Blade is one of the best tools to kill Terrorblade before he can use Sunder due to its high magical (pure with Laguna Blade damage is Pure and pierces Spell Immunity talent) burst damage.
* Dragon Slave and Light Strike Array allows Lina to clear Terrorblade's illusions from both, Conjure Image and Manta Style.
Legion Commander
* Duel's long duration prevents Terrorblade from swapping his health with Sunder.
* Overwhelming Odds deals high damage to Terrorblade's illusions.
Lina
* Lina's damage burst can quickly kill Clinkz before he saves them with 
Skeleton Walk.
* Fiery Soul attack speed bonus removes 
Burning Army easily in all stages of the game.
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.
Lina
* Venomancer has low health, which makes him vulnerable to Lina's heavy magic damage.
* Fiery Soul attack speed bonus removes 
Plague Wards easily in all stages of the game.
Legion Commander
* 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.
Lina
* Lina's high damage burst from Dragon Slave, Light Strike Array and Laguna Blade can easily kill Chen's allies or Chen himself before he can use 
Hand of God.
Additional:
* Lina's high damage burst from Dragon Slave, Light Strike Array and Laguna Blade can easily kill Chen's allies or Chen himself before he can use Hand of God.
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.
Lina
* Since Windranger is bad against magical damage, heroes with continuous magical damage or magical nukes can blast her: Zeus, Tinker, 
Leshrac, 
Viper, 
Skywrath Mage, Lion, Lina, 
Venomancer.
Legion Commander
* Press The Attack can save allies dispell from Shackleshot.
* Duel can lock before escape with Windrun.
* Focus Fire potentially trigger with Blade Mail can Windranger's useless.
Lina
* Heroes that can kill Death Prophet with nukes can prevent her from using Exorcism to its full duration or using it at all: Lina, Lion, 
Puck, 
Morphling.
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.
Lina
* Heroes with summons can find their summons eliminated easily by Lina, like 
Broodmother, Nature's Prophet, and Chen.
Additional:
* Light Strike Array in combination with Dragon Slave can easily clear Broodmother's spiders.
* Laguna Blade offers extensive damage that can kill Broodmother early on or before she is able to use Insatiable Hunger in attempts to salvage a fight.
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.
Lina
* Heroes with abilities that can pull Lina out of position can easily bring her to their team mates, like 
Batrider with 
Flaming Lasso, 
Pudge with 
Meat Hook and 
Vengeful Spirit with 
Nether Swap.
Lina
* Pudge has low armor and mobility, making him suspectible to her physical attacks (if Lina is the carry).
* Because 
Dismember is a channeled ability, it can be canceled through Light Strike Array within a distance.
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.
Lina
* Heroes with high magical burst can easily kill Huskar when he is at low health: Lion, Lina, Skywrath Mage
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.
Lina
* Enchantress has pitiful health, and cannot tank Lina's heavy magic damage.
* 
Untouchable is decently countered by Fiery Soul, exposing Enchantress' weakness to physical damage due to her low armor.
* Lina is decent at clearing creeps and can kill Enchantress' creeps quickly.
Additional:
* Enchantress has a very small health pool and cannot tank Lina's heavy magic burst.
* Untouchable is decently countered by 
Fiery Soul, exposing Enchantress's weakness to physical damage due to her low armor.
* Lina is decent at clearing creeps and can kill Enchantress's creeps quickly.
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.
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.
Lina
* Eul's Scepter of Divinity is an item Lina commonly buys, which in combination with and Light Strike Array can disable Mirana if she tries to Leap away.
* Laguna Blade's magical (pure with Laguna Blade damage is Pure and pierces Spell Immunity talent) burst damage takes advantage of Mirana's below average health.
Additional:
* 
Moonlight Shadow does little good against Dragon Slave and Light Strike Array.
* Lina's damage burst can quickly kill Mirana's teammates before she saves them with Moonlight Shadow.
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.
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.
Legion Commander
* Duel prevents Primal Beast from using all of his spells and stops all of his damage output.
* Moment of Courage will not proc if Primal Beast is using Trample so you may want to play around with that if you're looking for duel damage with a Blade Mail.
* Press the Attack can be used to dispel Pulverize immediately and make allies survive Trample for a short duration with the heal.
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.
Lina
* Laguna Blade deals amplified magical damage (pure from Aghanim's Scepter) to Necrophos when he is under the effects of 
Ghost Shroud.
Additional:
* Laguna Blade's damage as well as damage from all of Lina's abilities will be greatly amplified during Ghost Shroud.
Lina
* Laguna Blade ends Gyrocopter very quickly in the early to mid game.
Lina
* Heroes with high damage output who can burst down Morphling before he has time to use Attribute Shift (Strength Gain), like Lina and Lion.
Additional:
* Light Strike Array catches Morphling while he jumps in from 
Waveform and also prevents Morphling from using his abilities.
* Laguna Blade can kill Morphling quickly before he shifts into 
Attribute Shift (Strength Gain).
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
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.
Lina
* Dragon Slave deals reliable magic damage during the laning phase against Mars.
* Lina's Eul's Scepter of Divinity and Light Strike Array combo can interrupt Mars from being disruptive for a decent amount of time and leave him vulnerable for follow up stuns.
* Laguna Blade deals massive magical damage, and pure damage with Aghanim's Scepter.
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.
Lina
* Abilities that can destroy trees can give Hoodwink a disadvantage: 
Timbersaw, 
Windranger, Lina.
Legion Commander
* A well-timed 
Eclipse before a Duel usually prevents Legion Commander from winning Duels if Luna is the target. Luna can also buy Linken's Sphere to block Duel.
* Meanwhile, when Luna is not a target, Eclipse and 
Lucent Beam can also help an ally win a Duel against Legion Commander.
* Bear in mind, however, that skilled Legion Commander will always buy a Black King Bar to block Eclipse and Lucent Beam or Aghanim's Scepter to reduce their damage.
Additional:
* A well-timed Eclipse before a Duel usually prevents Legion Commander from winning Duels, if Luna is the target.
* Meanwhile, when Luna is not a target, Eclipse and Lucent Beam can also help an ally win a Duel against Legion Commander.
* However, skilled Legion Commander will always buy a Black King Bar to block Eclipse and Lucent Beam or Aghanim's Scepter to reduce it's damage.
Lina
* 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
* 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.
Lina
* Any hero who can counter-initiate in anticipation without getting caught in Reverse Polarity: 
Sven, 
Omniknight, Enigma, 
Luna, 
Naga Siren, 
Mars, 
Jakiro, Venomancer, 
Elder Titan, Faceless Void, Rubick, Keeper of the Light, 
Pugna, Invoker, 
Spectre, 
Alchemist, Treant Protector, Lina, Oracle, Zeus, Shadow Shaman, 
Phoenix, 
Razor, 
Huskar, Batrider, 
Kunkka, 
Tidehunter, Wraith King, 
Sand King, 
Medusa, 
Dawnbreaker.
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
* Heroes who have high health are a problem for Sniper because he likes to attack the closest target and sit at the back, much like a 
Terrorblade so when that hero doesn't die; he's forced to show his position for a very long time: 
Centaur Warrunner, Legion Commander, 
Primal Beast.
Additional:
* 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.
Lina
* Heroes with high burst damage: Lina, Lion, Luna, 
Nyx Assassin, 
Queen of Pain.
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
* 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.
Lina
* Heroes with powerful spammable abilities will prove problematic for Grimstroke as Ink Swell does not protect him from them: Zeus, Skywrath Mage, Tinker, Lina
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
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.
Legion Commander
* Silences and other types of lockdown that prevent Weaver from using his spells: 
Silencer, 
Riki, Lion, Legion Commander, Shadow Shaman, Bane.
Additional:
* Duel's long duration prevents Weaver from activating Time Lapse or escaping with 
Shukuchi.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen
Legion Commander
* 
Tethered heroes are much harder for Legion Commander to kill in Duels.
* 
Relocate can cancel Duels and save allies.
Lina
* Heroes with either magical, physical or pure damage burst: Bane, 
Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, Ursa, 
Void Spirit.
Legion Commander
* Duel is very effective against Io due to its low health and armor.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen
Legion Commander
* Heroes with strong area damage to destroy Phantasm illusions: Axe, Ember Spirit, Legion Commander, Phoenix
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
Lina
* Heroes with summons can find their summons eliminated easily by Lina, like Broodmother, Nature's Prophet, and Chen.
Additional:
* Lina can easily prevent Nature's Prophet's Teleportation escape attempts with Light Strike Array, and can clear Sprout's trees instantly.
* Lina's Dragon Slave and Light Strike Array can kill Nature's Prophet's Treants.
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.
Lina
* Heroes with abilities that can pull Lina out of position can easily bring her to their team mates, like Batrider with Flaming Lasso, Pudge with Meat Hook and Vengeful Spirit with Nether Swap.
Legion Commander
* Press the Attack dispels Flaming Lasso.
* Batrider is unlikely to win a Duel in any stage of the game.
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.
Lina
* Heroes with spell immunity until Lina takes Laguna Blade damage is pure and pierces spell immunity talent, like Lifestealer with Rage and Juggernaut with Blade Fury.
Legion Commander
* Duel pierces spell immunity and forces him to attack Legion Commander, making him unable to use 
Omnislash.
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
Lina
* Lina builds 
Shadow Blade (and upgrades it into a Silver Edge), which makes it hard for Ancient Apparition to land his abilities.
* Laguna Blade can kill Ancient Apparition easily due to his low health pool and lack of mobility.
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
* 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.
Lina
* Fragile support heroes are all ideal targets for the Phantom Assassin. Heroes such as Lina and Witch Doctor are all prime targets that may not be able to react quickly and fight back due to Phantom Assassin's sudden appearance.
Lina
* Laguna Blade is one of the best tools to kill Phantom Assassin before she can do anything in early-to-mid game due to its high magical (pure with Laguna Blade damage is Pure and pierces Spell Immunity talent) burst damage.
* 
Blur offers no protection against Lina's abilities. Likewise, Lina can counter Blur's evasion by buying either Silver Edge or 
Monkey King Bar.
* Lina just has to be careful about 
Fan of Knives from 
Aghanim's Shard and 
Coup De Grace, as Fan of Knives can deal pure damage to Lina and disable Fiery Soul awhile Coup De Grace can deal serious damage to her even if she is spell immune, which may force Lina to buy 
Ethereal Blade to deal with Phantom Assassin.
Additional:
* Laguna Blade is one of the best tools to kill Phantom Assassin before she can do anything in early-to-mid game due to its high magical (pure with Laguna Blade damage is Pure and pierces Spell Immunity talent) burst damage.
* Blur offers no protection against Lina's abilities. Likewise, Lina can counter Blur's evasion by buying either Silver Edge or Monkey King Bar.
* Lina just has to be careful about Fan of Knives from Aghanim's Shard and Coup De Grace, as Fan of Knives can deal pure damage to Lina and disable Fiery Soul awhile Coup De Grace can deal serious damage to her even if she is spell immune, which may force Lina to buy Ethereal Blade to deal with Phantom Assassin.
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 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.
Lina
* Heroes with abilities that can pull Lina out of position can easily bring her to their team mates, like Batrider with Flaming Lasso, Pudge with Meat Hook and Vengeful Spirit with Nether Swap.
Lina
* Lina can burst Vengeful Spirit down, provided she can land Light Strike Array before Vengeful Spirit lands her Magic Missile.
* Laguna Blade deals massive damage, often being enough to kill a squishy Vengeful Spirit.
Legion Commander
* 
Clinkz, Sniper, 
Lone Druid, Troll Warlord, Legion Commander and Wraith King are some of the Heroes that base themselves on attacks with little or no spell power, so they suffer in the grassy hands of Overgrowth.
Lina
* Light Strike Array and Dragon Slave allows Lina to destroy trees, countering 
Nature's Guise and 
Eyes in the Forest.
* Lina has many tools to remove 
Living Armor's protection.
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.
Lina
* Heroes who have channeled abilities can be stunned by Light Strike Array, like Witch Doctor with Death Ward and Bane's Fiend's Grip.
Legion Commander
* Heroes with strong dispels can dispel Bane's disables from their allies: Oracle, Legion Commander, Omniknight.
Legion Commander
* Song of the Siren lasts long enough to prevent a successful Duel (but only if Naga wasn't the target).
Lina
* Since Naga Siren is a hero who barely goes for Black King Bar, she is vulnerable to nukers with strong magical damage and big area-of-effect spells in every game more than any other carry heroes: Sand King, Jakiro, Leshrac, Lina, Earthshaker, Zeus.
Legion Commander
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, 
Chaos Knight, Terrorblade, Naga Siren
Lina
* 
Mind Flare does tons of damage against Lina because of her high intelligence.
* The mana burn from 
Vendetta also prevents Lina from casting her full combo.
* 
Spiked Carapace can easily be used to counter Lina's abilities because of their long cast animation, and could probably kill Lina outright if Laguna Blade is reflected.
Lina
* Heroes who build Black King Bar as either core or situational item will be able to fight back against Nyx Assassin and freely attack him as Spiked Carapace cannot pierce spell immunity at all: Axe, Broodmother, Dawnbreaker, Enigma, Huskar, Jakiro, Legion Commander, Lina, Luna, Lycan, 
Slardar, Slark, Troll Warlord, Witch Doctor.
Legion Commander
* Heroes who build Black King Bar as either core or situational item will be able to fight back against Nyx Assassin and freely attack him as Spiked Carapace cannot pierce spell immunity at all: Axe, Broodmother, Dawnbreaker, Enigma, Huskar, Jakiro, Legion Commander, Lina, Luna, Lycan, Slardar, Slark, Troll Warlord, Witch Doctor.
Additional:
* Duel's long duration prevents Nyx Assassin escaping from Vendetta. With Aghanim's Scepter, she can also bypass Spiked Carapace.
Lina
* Heroes that can close the gap can easily chase her down, such as Timbersaw with 
Timber Chain and 
Anti-Mage with 
Blink.
Lina
* Timbersaw has a difficult time against magical and pure damage: Lina, Leshrac, 
Enchantress, Queen of Pain
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.
Lina
* Heroes who can clear the waves of Enigma's Eidolons: Lina, Luna, Dawnbreaker, Jakiro, Shadow Shaman, 
Death Prophet, Keeper of the Light, Invoker, Leshrac, Puck.
Legion Commander
* Heroes with long or multiple disables will prevent Legion Commander from winning Duels: Shadow Shaman, Lion
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.
Lina
* Blink allows Anti-Mage to get on top of Lina and deal damage with his 
Mana Break.
* 
Counterspell makes Anti-Mage tanky against Lina's heavy magic damage.
* A well-timed Counterspell can block and reflect Laguna Blade.
* 
Mana Void is very strong against Lina, who has a high mana pool and quickly depletes it during fights.
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.
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.
Lina
* Laguna Blade can kill Dazzle quickly before he casts Shallow Grave.
Legion Commander
* 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.
Lina
* Dragon Slave will make quick work of the spawned illusions from Disruption.
* An attempt to save an ally using Disruption can easily become a perfect setup for a Light Strike Array for the enemy.
* Shadow Demon doesn't have the burst damage to take Lina out of the fight quickly, although Demonic Purge can help his allies kill a squishy Lina.
Lina
* Squishy heroes (
Io, Crystal Maiden, Lina...), as Earth Spirit can deal tons of damage with Magnetize.
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 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.
Lina
* Any hero with high attack speed will be a threat to Phoenix when it initiates, as they can easily tear down a 
Supernova, perhaps even while debuffed by Fire Spirits: Juggernaut, Clinkz, Troll Warlord, Beastmaster, Lina.
Lina
* 
Nethertoxin prevents buildup of Fiery Soul stacks.
* 
Corrosive Skin provides magic resistance against Lina's spells.
* 
Poison Attack and 
Viper Strike can burn away Lina's small health pool.
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.
Legion Commander
* Heroes with long or multiple disables will prevent Legion Commander from winning Duels: Shadow Shaman, Lion
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.
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.
Lina
* Light Strike Array catches Meepo and his clones if he tried to gank Lina with 
Earthbind & 
Poof.
* Laguna Blade can quickly kill Meepo and his clones before they escape with Poof.
Legion Commander
* Both Guardian Angel and Purification are perfect counters against Duel.
Additional:
* 
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.
Lina
* Guardian Angel is generally useless against Lina as she primarily relies on magical damage. Lina can also dispel it with Eul's Scepter of Divinity as she is a hero who often goes for it. Eul's Scepter of Divinity can later be upgraded into 
Wind Waker, which will allow Lina to escape from Omniknight.
* Laguna Blade can often finish off Omniknight's allies before he can save them with Purification and Heavenly Grace. This can become even worse once Lina picks Laguna Blade damage is pure and pierces spell immunity talent, which will allow it to ignore both, any form of spell immunity and Guardian Angel.
Lina
* Doppelganger can be used to easily dodge Light Strike Array if timed correctly.
* Phantom Lancer can quickly deplete Lina's mana pool with his illusions and deal massive damage from it simultaneously since Phantom Lancer is a natural 
Diffusal Blade carrier.
Legion Commander
* Overwhelming Odds deals high damage to Phantom Lancer's illusions.
* Duel's long duration prevents Phantom Lancer from using Doppelganger.
Lina
* Nether Ward will be problematic for heavy nukers and spammers like
Skywrath Mage, 
Lina, 
Lion and 
Invoker, but Pugna must not use Decrepify defensively against them as he will be helping them out more than anything.
Legion Commander
* Decrepify prevents Legion Commander from attacking allies during
Duel, regardless if it's used on her or on the ally . 
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.
* Pugna can easily cast Decrepify, Nether Blast and Life Drain on Legion during the 4/4.75/5.5/8 seconds of duel
Additional:
*
*