Ursa
* Plasma Field can spot an Ursa sneaking into Roshan's pit
* Static Link has a 800 link break distance, meaning Razor can stay close enough to drain Ursa' damage, but not too close to get attacked
* Static Link cannot be dispelled by 
Enrage
* With Storm Surge, Razor will usually be faster than Ursa in most cases
* Eye of the Storm melts through Ursa's armor
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.
Ursa
* Heroes who rely strongly on melee physical damage will fare badly against Omniknight's Guardian Angel: 
Phantom Assassin, 
Juggernaut, 
Dragon Knight, 
Lycan, 
Ursa, 
Troll Warlord
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.
Ursa
* Ursa struggles against heroes with strong (and especially undispellable) disables (
Disruptor, 
Puck, 
Shadow Demon, 
Outworld Destroyer and etc).
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.
Ursa
* Bane can use 
Nightmare and 
Fiend's Grip to lock down Ursa early game and in team fights, forcing Ursa to buy a Black King Bar and making him very vulnerable to being kited once his Black King Bar is down to 6 seconds.
* Overall, Bane's potent disables force Ursa to build more defensive items and play more defensively in general.
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.
Legion Commander
* Heroes with strong dispels can dispel Bane's disables from their allies: 
Oracle, 
Legion Commander, 
Omniknight.
Ursa
* Melee carries such as 
Sven, Ursa or 
Lifestealer can be slowed and easily kited with Demonic Purge.
Additional:
* Shadow Demon's 
Demonic Purge renders Ursa useless even through 
Black King Bar as it slows him, continually purges his Overpower charges and can not be dispelled by Ursa's Enrage.
* 
Disruption is a good way to save teammates against Ursa. Disrupting Ursa is also a good way to kite him, as it can not be dispelled by Enrage.
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
* 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
* 
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
* Solar Guardian can save allies who are being dueled and will interrupt her Duel initiation.
Ursa
* If Ursa uses Enrage Brewmaster can use Cyclone to render him harmless during his ultimate.
* Brewmaster has two spells to slow down Ursa, allowing his team to kite around him easily.
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.
Ursa
* Storm Spirit can steal 
Aegis of the Immortal during Roshan attempts through the Pit, because of his 
Ball Lightning.
* Ursa has no way to catch a slippery Storm Spirit, as Earthshock's slow will do nothing to stop Storm Spirit from using Ball Lightning.
Legion Commander
* 
Mystic Flare can easily burst down Legion Commander while she is Dueling.
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.
Legion Commander
* Earthshaker's AoE stuns can save ally against Duel, forcing Legion Commander to spend Aghanim's Scepter or Black King Bar.
Ursa
* Lion has two low cast point disables (
Hex and 
Earth Spike) to control Ursa before he buys a Black King Bar.
* Hex is one of the few abilities that cannot be dispelled even with an Aghanim's Scepter upgraded Enrage.
* Lion can control Ursa's low mana pool via 
Mana Drain.
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.
Ursa
* Slark can detect early Roshan attempts due to 
Shadow Dance if he frequently checks the Pit.
* Enrage cannot restore attributes stolen by 
Essence Shift and will reduce his physical damage output.
* Even if Ursa initiates with Earthshock, Slark can 
Pounce away or use 
Dark Pact after Ursa's initiation to avoid Fury Swipes' damage until Earthshock's slow is gone.
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
* 
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.
Ursa
* Primal Roar and the slow from Boars makes kiting Ursa very easy.
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.
Ursa
* Enchant can dispel 
Overpower.
* Enchant's slow can help kite Ursa in fights and also in lane.
* Enchantress can out harass Ursa in lane by using her long attack range and Untouchable, as well as out sustaining him with Nature's Attendants.
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
Ursa
* Laser can be cast on a initiating Ursa, normally causing him to waste multiple Overpower attacks, forcing him to either Black King's Bar, or Enrage to protect himself.
* Ursa will probably carry a Linken's Sphere to counter Tinker's Laser. Popping it with Scythe of Vyse is actually preferable, due to Laser's high Pure damage.
* While Ursa is a common Blink Dagger carrier, but he otherwise has no way to close the gap, Baiting him into using his Blink, then blinking away, allows Tinker to easily kite Ursa.
* Enrage is generally how Ursa disengages, Due to Tinker's high maneuverability, he can follow him until it runs out. then burst him down with high magic damage.
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.
Ursa
* Heroes who can provide constant vision inside the Roshan Pit can negate one of the strongest advantages of Ursa, which is the possibility of quickly killing Roshan at the early game, with minimum itemization needed (
Clockwerk, 
Beastmaster, etc).
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.
Ursa
* Ursa's high physical burst damage combined with his big attack speed and durability makes him a very bad target for Power Cogs.
* Even with 
Blade Mail, Ursa's Enrage will negate most of the reflected damage.
Ursa
* Heroes that rely on slows to get kills: Lifestealer, 
Night Stalker, Ursa, Phantom Assassin, 
Terrorblade.
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
Ursa
* Riki can detect early Roshan attempts because of Cloak and Dagger if he frequently checks the Pit.
* Ursa cannot Enrage when in Smoke Screen (Black King Bar will help though).
* Even if Ursa gets vision over him, Riki can Blink Strike away or use Tricks of the Trade after Ursa's initiation to avoid all 
Fury Swipes damage until 
Earthshock's slow is gone.
Additional:
* Riki can detect early Roshan attempts because of 
Cloak and Dagger if he frequently checks the Pit.
* Ursa cannot Enrage when caught in 
Smoke Screen and will miss his attacks (although Black King Bar will help with this issue).
* Even if Ursa gets vision over him and initiates with Earthshock, Riki can 
Blink Strike away or use 
Tricks of the Trade after Ursa's initiation to avoid Fury Swipes' damage until Earthshock's slow is gone.
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.
Ursa
* Ursa struggles against heroes with strong (and especially undispellable) disables (Disruptor, Puck, Shadow Demon, Outworld Destroyer and etc).
Ursa
* Assuming they have not bought anti-evasion items, attack-dependent heroes such as Ursa, Terrorblade or Lifestealer can be a minor threat for Phantom Assassin early in the game, and may even be completely dominated by her thanks to her evasion.
Ursa
* Melee heroes that get kited easily have hard times dealing with Puck without any lockdowns, as Puck is one of the most mobile heroes. Heroes like Sven, Lifestealer, Ursa and 
Alchemist may have problems to get to Puck without proper initiation items. They also lack reliable lockdowns, as their disables are easily avoidable for Puck, or are just a soft disable.
Legion Commander
* Troll Warlord's melee bash and high attack speed can often help him and his allies win Duels against Legion Commander.
Ursa
* Heroes who rely heavily on melee attacks and lack early spell immunity are easily blocked and interrupted by Ink Swell: Lycan, Ursa, Troll Warlord.
Ursa
* Heroes who can delivers a big chunk of damage in few hits will find themselves struggle against Templar Assassin's Refraction: Sven, Phantom Assassin, Ursa, Wraith King, Lifestealer
Additional:
* Templar Assassin usually places 
Psionic Traps inside the Roshan Pit (and can teleport herself to the traps with an Aghanim's Scepter), preventing Ursa from killing Roshan without getting noticed by the enemy team.
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.
Ursa
* Heroes with evasions: Phantom Assassin, 
Brewmaster, 
Hoodwink, 
Windranger.
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 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
Ursa
* Lycan's ultimate makes him immune to slows from Ursa's Earthshock as well as allowing him to outmaneuver Ursa during Enrage. Lycan can also easily chase down Ursa while shapeshifted, should Ursa try to flee.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen
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
* 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
Ursa
* Ursa cannot effectively fight against Phantasm's illusions with his single-target damage.
* Chaos Bolt's potentially long stun with Chaos Bolt gives Ursa little opportunity to Enrage.
Additional:
* Ursa has no way to clear illusions quickly, making him vulnerable to 
Chaos bolt and 
Phantasm combo.
* 
Reality Rift can quickly relocate or reinitiate on Ursa once the duration of Enrage is over.
* Phantasm can be used to dispel Earthshock's slow. 
Manta Style is another item that counter Ursa greatly.
* Ursa has low mobility, once jumped on by Reality Rift, Ursa struggles to escape.
Legion Commander
* Heroes with strong area damage to destroy Phantasm illusions: Axe, 
Ember Spirit, Legion Commander, Phoenix
Ursa
* 
Doom makes Ursa less disruptive, and it cannot be dispelled with Enrage upgraded with Aghanim's Scepter.
Ursa
* High health heroes (Axe, 
Doom) fall fast with Fury Swipes stacks.
Ursa
* Ursa has no sustained AoE to deal with illusions, it becomes worse since Phantom Lancer can create more illusions in a matter of seconds.
* 
Diffusal Blade can be used to drain Ursa mana. This is a standard item for Phantom Lancer in every match.
* 
Doppelganger applies basic dispel on Phantom Lancer, which will remove the slow from Earthshock. It also resets fights with more illusions, making hard for Ursa to hit the real Phantom Lancer.
* Manta Style creates two more illusions and also applies a basic dispel, further complicating the problem for Ursa to deal with.
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.
Ursa
* Enrage with Aghanim's Scepter can dispel Flaming Lasso.
Legion Commander
* Press the Attack dispels Flaming Lasso.
* Batrider is unlikely to win a Duel in any stage of the game.
Ursa
* Earthshock can slow down Chen and deal damage to both, Chen and his creeps.
* Many stacks from Fury Swipes combined with Overpower can guaranatee a kill for Ursa before Chen can save his allies with 
Hand of God.
* Enrage only makes Chen's attacks and his creeps's attacks tickle Ursa.
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.
Ursa
* Ursa can deal lots of damage during the laning phase before Terrorblade can have 
Sunder available.
* Even if Terrorblade succeeds to use Sunder on Ursa, Enrage's damage reduction can help Ursa survive after Terrorblade has used Sunder him while also making Terrorblade's attacks tickle, even during Metamorphosis for it's duration.
Legion Commander
* Duel's long duration prevents Terrorblade from swapping his health with Sunder.
* Overwhelming Odds deals high damage to Terrorblade's illusions.
Ursa
* Low armor and lack of escape makes Pudge vulnerable to Ursa, specially when he gets his Blink Dagger.
* If Pudge lands a 
Meat Hook on Ursa, Ursa can simply face Pudge head on provided he can burst him down before any follow up disables.
* Enrage's Aghanim's Scepter upgrade allows Ursa to dispel Pudge's 
Dismember.
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.
Ursa
* Fury Swipes is not protected by 
Blade Fury and allows Ursa to harass Juggernaut anytime.
* Enrage reduces the damage taken from 
Omnislash.
Legion Commander
* Duel pierces spell immunity and forces him to attack Legion Commander, making him unable to use Omnislash.
Ursa
* 
Fade Bolt is not enough to burst Ursa, and even more so with Enrage active.
* The damage reduction from Fade Bolt is not effective due to Fury Swipes.
* Enrage lessens the lockdown duration from 
Telekinesis due to its status resistance.
* Ursa can easily melt 
Rubick down with Fury Swipes and Overpower if he gets close enough.
* Few of Ursa's spells grants utility for Rubick, as Rubick cannot steal the Fury Swipes passive.
* Enrage provides Rubick with some sort of survivability, yet Rubick generally wastes the duration in the front line as he does not have a constant damage source.
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
Ursa
* Early game gankers can make life very difficult for a Sniper if he keeps being caught: Ursa, 
Pudge, 
Earth Spirit.
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.
Ursa
* Jumping on Ursa with Life Break is often suicide for Huskar, as he will be immediately bursted down with Fury Swipes.
Additional:
* Huskar likes fights with a long duration and is usually at low health, making him vulnerable against Ursa's physical damage.
* Jumping in with Life Break against Ursa is suicide, as Enrage, Overpower, and Fury Swipes will easily shred Huskar.
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.
Ursa
* Enrage reduces the damage from Blade Mail and Counter Helix to a minimum, forcing Axe to play around Ursa's ultimate ability.
* Overpower and Fury Swipes stacks damage overwhelming for Axe, despite his high health.
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.
Ursa
* Silencer relies on preventing enemies from using abilities in teamfights with Arcane Curse, Last Word, and Global Silence. However, they are ineffective against Ursa since he relies more on items and attacks than abilities.
* Against a carry Silencer, Enrage can help Ursa reduce all damage he takes, even Glaives of Wisdom's pure damage will just tickle Ursa while his Enrage is active.
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.
Ursa
* Ursa can shred Warlock's Golems in a few seconds with Fury Swipes and Overpower.
Legion Commander
* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen
Ursa
* Heroes with burst damage of their own won't be afraid to go toe to toe with Void Spirit, like Ursa, Lifestealer, or Axe.
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
* 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.
Ursa
* 
Light Strike Array has a long delay, making her vulnerable for Ursa's burst.
* Enrage can protect Ursa against Lina's high magical burst.
Ursa
* Fury swipes can tear Dragon knight down as it stacks infinitely.
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.
Ursa
* Timbersaw's physical survivability revolves around 
Reactive Armor, which is largely ignored by Fury Swipes due to the extreme amounts of damage it does in a very few number of attacks.
* Timbersaw's burst damage will not do much against Enrage, although he could easily use 
Timber Chain to escape, wasting the duration of it.
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.
Ursa
* Fury Swipes will keep stacking on Tidehunter since it cannot be dispelled by Kraken Shell and its bonus damage cannot be reduced by Anchor Smash.
* Enrage dispels the slow from Gush, and if upgraded with Aghanim's Scepter, can even dispel Ravage's stun.
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
* 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.
Ursa
* Ursa can do damage very fast with his Overpower and Fury Swipes abilities, Necrohops will have taken large amounts of damage before he can use Ghost Shroud, And if Ursa has 
Skull Basher, Ursa will quickly demolish Necrophos before he can do anything to retaliate.
* Skilled and smart Ursa can bait Necrophos into using Reaper's Scythe on him, and with his Aghanim's Scepter upgraded Enrage that can negate 80% of the damage, Ursa will often survive and waste Reaper's Scythe.
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.
Ursa
* Earthshock prevents Shadow Fiend from escaping after Ursa used his Blink Dagger to get on top of him.
* Overpower and Fury Swipes allow Ursa to quickly kill Shadow Fiend.
* Enrage keeps Ursa alive in a manfight with Shadow Fiend and allows him to stay close, even if Shadow Fiend uses Requiem of Souls.
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.
Ursa
* Chemical Rage will rarely save Alchemist against Ursa's Fury Swipes.
* Enrage allows Ursa to both be a threat to Alchemist and avoid his over time damage.
Legion Commander
* Duel's long duration prevents Nyx Assassin escaping from 
Vendetta. With Aghanim's Scepter, she can also bypass 
Spiked Carapace.
Ursa
* Ursa's massive physical damage can destroy Kunkka quickly.
* Enrage can be activated before being hit by Ghostship to prevent most of the damage.
* Earthshock slows Kunkka's movement speed. With no escape abilities, Kunkka is easy prey.
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
Ursa
* Due to Tiny's non-existent agility gain, high physical damage heroes are more effective against him (
Clinkz, 
Templar Assassin, Ursa, Wraith King etc).
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
* 
Tethered heroes are much harder for Legion Commander to kill in Duels.
* 
Relocate can cancel Duels and save allies.
Ursa
* 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 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 with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, Lich, Techies, Rubick
Ursa
* Low mobility heroes: Heroes with no/little means of traveling fast have difficulty getting to/away from Bounty Hunter due to his slowing Jinada and hastening Track. Few examples of such heroes are: Crystal Maiden, 
Sniper, Ursa, 
Witch Doctor, etc.
Ursa
* Ursa with Enrage
* 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
* 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 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
* 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
Ursa
* Enrage will make it very difficult to burst him down.
* Zeus has little armor, HP and mobility; Ursa's favorite kind of target.
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.
Ursa
* Ursa can easily unleash a number of attacks in an incredibly short amount of time, easily destroying the 
Supernova in a couple of seconds regardless of Fire Spirits' debuff. His Enrage also dampens any damage Phoenix might toss at his direction, as well as remove any debuffs Phoenix may place on him.
Ursa
* With Aghanim's Scepter, Broodmother will gain access to 
Spinner's Snare, which will allow her to create invisible lines on her webs from 
Spin Web that will root, deal damage over time, and reveal enemy heroes if they unwittingly step on them. This allows Broodmother to keep her allies alerted on heroes who rely on invisibility-themed and movement-themed abilities and items to surprise enemy heroes and disrupt ganking attempts of enemy heroes: Phantom Assassin, Nyx Assassin, 
Mirana, 
Bounty Hunter, Templar Assassin, Riki, 
Spirit Breaker, 
Anti-Mage, Tusk, Ursa, Nature's Prophet, 
Enigma, Void Spirit, 
Magnus etc.
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.
Ursa
* With Aghanim's Scepter upgraded Infest, Lifestealer can use it on enemy heroes to attack them and disarm them from inside, even if they are spell immune, which can give him the edge over the heroes he's weak against like Ursa, Phantom Assassin, Terrorblade or Troll Warlord.
Ursa
* Lifestealer will struggle to duel Ursa in all stages of the game due to Fury Swipes, which pierces magic immunity. Ursa can also stand up to Lifestealer with Enrage, which dramatically reduces incoming damage and further delay Lifestealer's Feast.
Additional:
* Lifestealer's 
Feast will most likely not out-heal the damage from Fury Swipes and Overpower in the early to mid game.
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.
Ursa
* Ursa is a special mention because despite Bulwark diminishing most of the damage Ursa does, he is quite durable, especially with Enrage, discouraging the aggressive all-in playstyle of Mars; Ursa can simply not target 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
* 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.
Ursa
* 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 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 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 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.
Ursa
* 
The swarm beetle can waste Ursa's Overpower attacks.
* Ursa has no inherent way of disabling a slippery Weaver by preventing him from 
Shukuchiing or Time Lapseing away, as the slow from Earthshock is useless against Shukuchi's haste effect.
Additional:
* Earthshock's slow is ignored by Shukuchi.
* Ursa can be kited with Shukuchi and his burst damage will be negated with Time Lapse as long as Weaver survives it.
* The Swarm breaks Ursa's Blink Dagger, forcing him to deal with the beetles.
Legion Commander
* Duel's long duration prevents Weaver from activating Time Lapse or escaping with Shukuchi.
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
Ursa
* If Ursa uses Enrage, Pugna's Life Drain is next to worthless against him, due to Ursa taking 80% less damage, therefor Pugna heals by only 20% of the damage that the spell normally deals.
* It also dispels Decrepify, Even if you wait until he casted it, he can still dispel it with Shard upgraded Earthshock
* Ursa also commonly builds Skull Basher. With his high Attack Speed from Overpower. he can easily cancel Life Drain
* If Decrepify is defensivly casted, Ursa can still cast Earthshock both to slow you, and to deal amplified magic damage. He also commonly builds a 
Nullifier
* If Ursa jumps on you with a Blink Dagger he can easily wipe you out with Overpower.
* Ursa's Overpower can destroy a full health 
Nether Ward and still have a few swipes leftover, Also Ursa's low mana spells means he takes negligible damage from the Nether ward anyway.
* Ursa is also a common Diffusal Blade carrier, using it to both amplify his damage, but as his primary way to catch fleeing heroes
* Pugna is also the primary target of Ursa, due to him being both quite squishy, and a serious threat to his team, Ursa prioritizes the weakest link as Fury Swipes stacking damage will quickly demolish them, allowing Ursa to safely switch heroes
Ursa
* Ursa relies on the Blink-Earthshock combo to slow enemies to burst them, but Windranger can use 
Windrun to escape through Earthshock's duration.
* Windrun and 
Focus Fire can easily allow Windranger to kite Ursa and do good amounts of damage in the process.
Additional:
* Windranger can avoid Ursa's primary source of damage, Fury Swipes, by simply using Windrun. The slow from Earthshock is also rendered irrelevant by Windrun.
* Focus Fire and Windrun can be used to kite Ursa.
Legion Commander
* Press The Attack 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.
Ursa
* 
Viper Strike is a strong and breaks Fury Swipes, undispellable slow, making it much easier to kite Ursa for everyone.
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.
Ursa
* Positioning-reliant heroes (Windranger, Tidehunter, Ursa...), since Earth Spirit can disrupt positioning with his Boulder Smash.
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
* 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.
Ursa
* Enigma lacks burst damage, and that makes him vulnerable to heroes who can recover themselves and turn the fight around to their advantage after Enigma finishes his initiation: Faceless Void, Terrorblade, Ursa, Weaver, 
Broodmother, Slark, Abaddon, Wraith King, Lifestealer.
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
* 
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.
Ursa
* Even though Ursa is a hero who relies on direct attacks to be effective, Fury Swipes does not work on allies if Ursa is affected by Winter's Curse, mitigating a majority of Ursa's damage. In addition, Ursa's unimpressive attack speed and attack damage without Overpower and Fury Swipes means that he deals little to no damage to allies during Winter's Curse.
* Aghanim's Scepter upgraded Enrage allows Ursa to survive Winter Wyvern's initiation with Winter's Curse.
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.
Ursa
* Fury Swipes damage is not reduced by Atrophy Aura, essentially bypassing Underlord's only natural defense.
* Enrage can easily dispel the root of 
Pit of Malice.
* However, Ursa has nothing to intercept Underlord and his team when they are grouped up for the teleportation with Fiend's Gate outside of Earthshock.
Ursa
* Heroes with weaker mobility will struggle to keep up with Night Stalker: 
Gyrocopter, Ursa, 
Drow Ranger
Ursa
* Heroes with stronger lane presence that can threaten to kill him: 
Batrider, Juggernaut, Ursa, 
Monkey King, 
Razor.
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.
Ursa
* Ursa's status resistance from Enrage reduces duration of Medusa's Stone Gaze.
* Ursa can stack damage with Fury Swipes easily against her Mana Shield in a prolonged team match.
Additional:
* Medusa's tankiness doesn't help her very much against Fury Swipes in long teamfights.
* With no escape mechanism and a slow movement speed, getting jumped on by Ursa usually spells a quick end for Medusa in the early game.
Ursa
* Slardar is one of the few meele heroes who can lane against Ursa in the early game, out harassing him with Bash of the Deep, and running away from a bad engagement with Guardian Sprint
Enrage defensively instead of offensively
* Corrosize Haze can force Ursa to cast
* With Corrosize Haze, Slardar's team can quickly dispatch of Roshan, denying one of Ursa's greatest advantages
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.