Warlock
* 
Ice Blast cancels Warlock's Golem's and Shadow Word's healing.
* 
Cold Feet stuns Warlock if he stands in place, forcing him to stop channeling Upheaval immediately or be forced to stop channeling it by it's stun.
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
Warlock
* 
Ursa can shred Warlock's Golems in a few seconds with 
Fury Swipes and 
Overpower.
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
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.
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.
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
* 
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.
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.
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.
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.
Legion Commander
* Solar Guardian can save allies who are being dueled and will interrupt her Duel initiation.
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
* 
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
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.
Warlock
* A pre-placed 
Fire Remnant allows Ember Spirit to escape Upheaval.
* 
Flame Guard blocks Shadow Word's damage.
* 
Sleight of Fist allows Ember Spirit to attack from outside of Upheaval's range, and 
Searing Chains lets him interrupt it.
Warlock
* 
Upheaval does not interrupt Slark too much, as he can just Pounce out of the area.
* 
Fatal Bonds and 
Shadow Word can be dispelled by Dark Pact.
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
* 
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
* 
Mystic Flare can easily burst down Legion Commander while she is Dueling.
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.
Warlock
* Ghostship helps your team soak up damage from 
Chaotic Offering and hit summons hard.
* Tidebringer clears summons later in the game.
* Most of your spells can interrupt Upheaval.
Warlock
* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: 
Beastmaster, 
Broodmother, 
Enigma, Nature's Prophet, 
Visage, 
Warlock, 
Wraith King.
Additional:
* 
Surge allows for Dark Seer and his allies to escape from Upheaval due to it ignoring any slow.
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".
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
* 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.
Warlock
* Heroes with channeling spells are very easy targets for Jakiro's abilities: 
Crystal Maiden, 
Dawnbreaker, Enigma, 
Pudge, 
Shadow Fiend, 
Shadow Shaman, Warlock.
Warlock
* Because all of Warlock's abilities are active abilities, silences can make his impact in fights minimal. Be cautious of heroes that carry silences like 
Death Prophet, 
Puck, and the aforementioned 
Silencer.
Warlock
* Heroes that have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include Crystal Maiden, 
Witch Doctor, Warlock or Shadow Fiend.
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
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.
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
* 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.
Warlock
* Supports with useful teamfight or contribution spells will be helpless against Doom: 
Dazzle, 
Oracle, Warlock.
Additional:
* 
Doom will not only prevent Warlock from casting his abilities in team fights, but also it reduces the healing from Shadow Word.
* 
Devour allows Doom to acquire a stun from neutral creeps, allowing him to interrupt Upheaval without having to use Doom.
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.
Warlock
* Because Warlock's abilities are all active abilities, Silencer can make his impact minimal.
* 
Arcane Curse prevents Warlock from using his abilities without increasing it's duration, which since all of Warlock's abilities are actives it is very effective against him.
* 
Last Word can prevent Warlock from casting his Fatal Bonds, Chaotic Offering, and Upheaval combo.
* 
Global Silence can nullify Warlock's impact in fights by preventing him from casting Fatal Bonds and Chaotic Offering, or by interrupting his Upheaval.
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
* 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
* Earthshaker's AoE stuns can save ally against Duel, forcing Legion Commander to spend Aghanim's Scepter or 
Black King Bar.
Warlock
* Warlock often stays back and counter-initiates by dropping his Chaotic Offering on Earthshaker and his allies.
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.
Warlock
* Channeling heroes will not go well against Warlock, especially those who build Black King Bar as Warlock's ultimate ability stun goes through spell immunity. E.g.: Crystal Maiden, Witch Doctor, Enigma, etc.
Warlock
* Warlock's signature Chaotic Offering can be devastating if stolen and dropped on multiple heroes.
* Telekinesis interrupts Upheaval when used on Warlock. Alternatively, Rubick can also cast this on a naerby creep or hero and drop them near Warlock to interrupt its channeling. When upgraded with 
Aghanim's Shard, Rubick can also use it to save an ally (or himself) from its area slow and damage.
* Fatal Bonds provides Rubick with a decent farming and harassing tool in the early game.
* Shadow Word provides some utility by healing Rubick and his team, and also as a harassment tool when used on enemies in the laning stage.
* Upheaval slows and damages enemies in an area, and it works exactly the same when casted by Rubick. Furthermore, he can extend its range and debuff amplification with Arcane Supremacy.
* A stolen Chaotic Offering can also be used to interrupt Upheaval while Telekinesis is on cooldown.
* It is advised to build items around Chaotic Offering as Rubick. Aghanim's Scepter, 
Octarine Core and 
Refresher Orb are all legitimate item choices.
Additional:
* All of Warlock's abilities are worthy choices for Rubick to 
Spell Steal, primarily Chaotic Offering. Furthermore, stolen abilities are also affected by the increased cast range and spell amplification from 
Arcane Supremacy.
* 
Telekinesis interrupts Upheaval when casted on Warlock, or to save allies (or himself) from its area slow and damage with Aghanim's Shard.
* Bear in mind that Warlock likes to cast his abilities in quick succession, so the time window left for Rubick to steal Warlock's ultimate can be short.
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.
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
* Magnetic Field prevents Legion Commander from getting wins with Duel.
Additional:
* 
Magnetic Field prevents Legion Commander from easily gaining wins with Duel.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: 
Lycan, 
Arc Warden, Warlock, 
Chen
Legion Commander
* 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.
Additional:
* 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.
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.
Warlock
* 
Shapeshift allows Lycan to escape from Upheaval with maximum movement speed.
* Warlock doesn't have a good solution to deal with Lycan's wolves from 
Summon Wolves.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen
Legion Commander
* Song of the Siren lasts long enough to prevent a successful Duel (but only if Naga wasn't the target).
Legion Commander
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: 
Phantom Lancer, 
Chaos Knight, 
Terrorblade, 
Naga Siren
Warlock
* Warlock is a very strong hero when positioned correctly, and his long cast range helps him with this. However, some heroes might disrupt or sneakily pass through his allies and deal with him, preventing him from doing his job. Such heroes include Chaos Knight, 
Spirit Breaker, 
Riki, and more.
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.
Warlock
* Illusion and heroes with summons are difficult to kill with Chen's single-target offensive spells: Terrorblade, Phantom Lancer, Chaos Knight, Broodmother, Naga Siren, Lycan, Visage, Beastmaster, Warlock, Wraith King. And even though Chen can convert enemy summons with Holy Persuasion, their much greater numbers will often overwhelm Chen and his creeps.
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.
Warlock
* Channeling heroes will not go well against Warlock, especially those who build Black King Bar as Warlock's ultimate ability stun goes through spell immunity. E.g.: Crystal Maiden, Witch Doctor, Enigma, etc.
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.
Warlock
* Viper cannot interrupt heroes with powerful channeling abilities: Bane, Enigma, Shadow Shaman, Warlock
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.
Warlock
* While heroes with strong mobility are able to get close or flee from Upheaval, heroes with no escaping abilities or that lack long disables will perish against Warlock. Once the Warlock Golem lands with its stun, its hardly possible to escape when he casts Upheaval. Notable examples: 
Huskar, 
Drow Ranger, Lion, 
Elder Titan, etc.
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.
Warlock
* Warlock Golems do plenty of physical and pure damage to bring down Huskar when he is at low health. Warlock is always a hazard for Huskar to initiate by using 
Life Break, because Chaotic Offering can stun him instantly, even when Black King Bar is activated, and allows Warlock's team to gather their wit and retaliate.
* After using Life Break to jump in, Huskar will not have any means to escape Upheaval. Which since he is an attack-dependent hero, this will nullify his impact in fights.
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.
Warlock
* Chaotic Offering can stop heroes who like to use spell immunity and teleport scrolls to safely farm during the early to mid game, since it stuns and also goes through spell immunity. Notable examples: 
Juggernaut, Lifestealer.
Legion Commander
* Duel pierces spell immunity and forces him to attack Legion Commander, making him unable to use 
Omnislash.
Legion Commander
* Press the Attack dispels Flaming Lasso.
* Batrider is unlikely to win a Duel in any stage of the game.
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.
Warlock
* Chaotic Offering's vast area-effect can destroy trees and stun Hoodwink.
* Upheaval makes retreating with 
Scurry difficult.
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.
Warlock
* Warlock has strong counter initiation which reduces Marci's effectiveness throughout the game.
* Fatal Bonds cancels 
Blink Dagger, which means Marci can move in and out of fights less effectively.
* Chaotic Offering paired with Upheaval provides a ministun, a movement slow and paired with Fatal Bonds has the potential to deal a lot of damage to Marci while she jumps on a target. The ministun also means that Marci will have a harder time casting Rebound. If Warlock does build Aghanim's Scepter and Refresher Orb, the physical damage from Golems will overwhelm Marci, especially when played as a support.
Legion Commander
* Duel's long duration prevents Terrorblade from swapping his health with 
Sunder.
* Overwhelming Odds deals high damage to Terrorblade's illusions.
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.
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.
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.
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.
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.
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 with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, Lich, Techies, Rubick
Warlock
* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.
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
Warlock
* Heroes with channeling spells because Shadow Fiend has nothing to cancel channeling outside of Requiem of Souls: Bane, Enigma, Pudge, Shadow Shaman, Dawnbreaker, Warlock, Crystal Maiden.
Additional:
* Because Shadow Fiend lacks escaping mechanisms, and is dependent on fair positioning for channeling 
Requiem of Souls, it's easier for Warlock with his long range crowd control abilities to lock Shadow Fiend down for his team.
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
* 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 with long or multiple disables will prevent Legion Commander from winning Duels: Shadow Shaman, Lion
Warlock
* While heroes with strong mobility are able to get close or flee from Upheaval, heroes with no escaping abilities or that lack long disables will perish against Warlock. Once the Warlock Golem lands with its stun, its hardly possible to escape when he casts Upheaval. Notable examples: Huskar, Drow Ranger, Lion, Elder Titan, etc.
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.
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
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
* 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
* 
Tethered heroes are much harder for Legion Commander to kill in Duels.
* 
Relocate can cancel Duels and save allies.
Warlock
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.
Legion Commander
* Duel is very effective against Io due to its low health and armor.
Warlock
* While heroes with strong mobility are able to get close or flee from Upheaval, heroes with no escaping abilities or that lack long disables will perish against Warlock. Once the Warlock Golem lands with its stun, its hardly possible to escape when he casts Upheaval. Notable examples: Huskar, Drow Ranger, Lion, Elder Titan, etc.
Warlock
* Heroes with summons: Lycan, Broodmother, Visage, Nature's Prophet, Warlock.
Warlock
* Because all of Warlock's abilities are active abilities, silences can make his impact in fights minimal. Be cautious of heroes that carry silences like Death Prophet, Puck, and the aforementioned Silencer.
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
* 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.
Warlock
* Chaotic Offering's spell immunity piercing stun can stop Black Hole's channeling. Due to this ability's large area of effect, it can be cast at a safe distance from the Black Hole. It also goes through Black King Bar and ignores Linken's Sphere.
* Fatal Bonds and Aghanim's Shard upgraded Shadow Word can be used to make Enigma's Eidolons easier to kill, potentially feeding the enemy team. Also,their constant damage will put Blink Dagger on cooldown, potentially forcing Enigma to prematurely activate Black King Bar.
Additional:
* Chaotic Offering pierces spell immunity and is an area of effect ability, therefore it doesn't matter if Enigma buys Black King Bar or Linken's Sphere, Warlock will always be able to cancel the channeling of 
Black Hole.
* Enemies often get clumped up around Black Hole to hit your allies, giving you a perfect opportunity to cast Fatal Bonds, Chaotic Offering, and Upheaval on multiple enemies.
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.
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.
Warlock
* Heroes with illusions and summons can swarm and overwhelm Bane, who has no area abilities to deal with them outside from Aghanim's Shard upgraded 
Brain Sap: Broodmother, Chaos Knight, Naga Siren, Nature's Prophet, Phantom Lancer, Terrorblade, Visage, Warlock, Wraith King.
Legion Commander
* Heroes with strong dispels can dispel Bane's disables from their allies: Oracle, Legion Commander, Omniknight.
Legion Commander
* 
Untouchable makes Enchantress one of the hardest heroes for Legion Commander to Duel against, as her attack speed will be significantly slowed for the duration, even with any form of spell immunity.
* Meanwhile, when Enchantress is not a target, Enchantress can use both 
Impetus and 
Enchant on Legion Commander to help her ally win the Duel.
Warlock
* Enchant can not control golem Chaotic Offering from Warlock.
Warlock
* Fragile supports with low armor are always a good prey, also her Psionic Trap will wear down most attempts to flee with their built-in disables: Silencer, Crystal Maiden, Warlock, Ancient Apparition, 
Grimstroke, Witch Doctor
Warlock
* Because Templar Assassin does not have escape potential in lane, any support hero with roaming potential and a 
Dust of Appearance can be great at shutting her down early game: Earth Spirit, Spirit Breaker, Tusk, 
Bounty Hunter, Riki, Warlock.
Additional:
* Warlock can cast Upheaval when Templar Assassin uses 
Meld, preventing her from escaping at the right moment.
* Warlock can also send his Warlock Golem near where she used Meld, preventing escape by Blink Dagger due to the Warlock Golem's 
Permanent Immolation.
* Warlock's Golem's Permanent Immolation will burn away 
Refraction with its damage over time.
Warlock
* Warlock is a very strong hero when positioned correctly, and his long cast range helps him with this. However, some heroes might disrupt or sneakily pass through his allies and deal with him, preventing him from doing his job. Such heroes include Chaos Knight, Spirit Breaker, Riki, and more.
Legion Commander
* Heroes with strong area damage to destroy Phantasm illusions: Axe, 
Ember Spirit, Legion Commander, Phoenix
Warlock
* Warlock is a very strong hero when positioned correctly, and his long cast range helps him with this. However, some heroes might disrupt or sneakily pass through his allies and deal with him, preventing him from doing his job. Such heroes include Chaos Knight, Spirit Breaker, Riki, and more.
Warlock
* Heroes with summons and illusions as Spirit Breaker has no strong AoE capabilities to deal with them: Chaos Knight, Phantom Lancer, Terrorblade, Naga Siren, Broodmother, Warlock, Visage, Nature's Prophet, Shadow Shaman, Lycan, Wraith King.
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
* Legion Commander's Overwhelming Odds deals damage for every Treant it hits, which allows it to easily wipe out large waves of them.
Warlock
* 
Impale and 
Spiked Carapace interrupts Upheaval with ease.
* Warlock's low health pool, mobility, and high intelligence gain makes him a prime target for Nyx Assassin's burst damage.
Legion Commander
* Duel's long duration prevents Nyx Assassin escaping from 
Vendetta. With Aghanim's Scepter, she can also bypass Spiked Carapace.
Warlock
* 
Mana Break prevents Warlock from casting his spells, particularly in the laning phase.
* 
Blink allows Anti-Mage to escape from Upheaval.
* 
Counterspell reduces damage from Shadow Word and Warlock's Golem's Permanent Immolation passive. Additionally, it can reflect Shadow Word and Fatal Bonds.
* 
Mana Void deals heavy damage after Anti-Mage has drained Warlock's large mana pool.
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.
Warlock
* Weaver's 
Shukuchi allows him to escape from Warlock's Upheaval with high move speed.
* Time Lapse allows Weaver to ignore damage from Warlock's Golem and escape.
Legion Commander
* Duel's long duration prevents Weaver from activating Time Lapse or escaping with Shukuchi.
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.
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
* 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.
Warlock
* Fatal Bonds links the Meepos together, which combined with area of effect damage or Cleave will be devastating.
Warlock
* With God's Strength, Warlock's Golem from
Chaotic Offering will go down in a matter of seconds. The two weaker golems granted by 
Aghanim's Scepter will fare worse due to 
Great Cleave hitting both.
Aghanim's Scepter upgraded 
Storm Hammer 
Aghanim's Scepter can dispel 
Shadow Word.
God's Strength combined with 
Great Cleave destroys Chaotic Offering golems within seconds.
Warcry gives Sven and his allies armor to help against Warlock's Golem's heavy physical damage and movement speed to help escape Upheaval.
Storm Hammer disrupts Upheaval.
*
Additional:
*
*
*
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.