* Slardar can use Guardian Sprint with Blink Dagger or Shadow Blade to get close, and Slithereen Crush will stun Sniper, making him vulnerable to Slardar's teammates.
* Corrosive Haze lowers Sniper's armor and makes Sniper's Shadow Blade useless, easily killing him with a few attacks.

* Sniper's low mobility and lack of defensive abilities makes him an easy gank target for the entire game, especially if Blink Dagger is picked up.

* Guardian Sprint allows Slardar to outrun Bristleback, even when slowed by Viscous Nasal Goo.
* Corrosive Haze's armor reduction makes Bristleback much less tanky.

* 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.

* Corrosive Haze lowers armor and reveals Pudge's location, making it hard to use Meat Hook on Slardar's teammates or Slardar himself.
* Because Corrosive Haze also reduces armor, it amplifies Bash of the Deep's damage.
* Slithereen Crush interrupts Pudge during Dismember at close range.
* Guardian Sprint allows Slardar to avoid Meat Hook.
Additional:
* While Slardar has Guardian Sprint activated, Rot cannot slow him and Meat Hook is easier to avoid.
* Slithereen Crush allows Slardar to interrupt Dismember at close range (when Slardar is not a target).
* Corrosive Haze reveals Pudge's location, making it very difficult for him to land hooks from the fog.

* Legion Commander can use Press the Attack on an ally to dispel the disable of 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.

* Duel's long duration prevents Weaver from activating Time Lapse or escaping with Shukuchi.

* Weaver relies on Shukuchi to escape and kite enemy heroes. Slardar's Corrosive Haze lowers armor and reveals Weaver, who is already a very frail target.
* Weaver usually builds Linken's Sphere, Corrosive Haze can be used to "pop" the spell block of Linken's Sphere, additionally the level 25 undispellable talent will prevent Weaver from removing Corrosive Haze with Time Lapse, allowing allied heroes to use their abilities on Weaver.
Additional:
* Corrosive Haze lowers armor and reveals Weaver during Shukuchi, who is already a frail target. In addition, Weaver usually builds Linken's Sphere, and Corrosive Haze can be used to "pop" the spell block. His level 25 talent can also make Corrosive Haze undispellable by Time Lapse, which puts Weaver in an even worse situation.
* Guardian Sprint can dodge Weaver's bugs with the movement speed bonus.

* Slithereen Crush and Bash of the Deep prevent Anti-Mage from using Blink, the latter even if Anti-Mage activates Black King Bar.
* Corrosive Haze allows allies to take down Anti-Mage before he has a chance to Blink, and maintains vision over him even if he does Blink away.

* Duel renders Anti-Mage's escape capabilities with Blink and Counterspell useless.
* 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.

* Clinkz survivability depends entirely on Skeleton Walk. Corrosive Haze not only makes its invisibility useless, but also makes Clinkz even more vulnerable to physical damage.
Additional:
* Slardar can reveal Clinkz with Corrosive Haze and make him easy to kill, and his Bash of the Deep also hits hard against Clinkz's naturally low health pool.
* Slardar's Guardian Sprint can catch up with Clinkz's Skeleton Walk.
* The stun and slow from Slardar's Slithereen Crush can hold Clinkz in place.

* Searing Arrows and Clinkz physical damage items is 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 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.

* Slardar's Corrosive Haze provides True Sight on its target, thus exposing Bounty Hunter's position regardless of Shadow Walk. In addition, Slardar's Guardian Sprint gives a very high movement speed bonus allowing him to chase Bounty Hunter even if Slardar is tracked.
Additional:
* Bounty Hunter's Shadow Walk is rendered useless with Corrosive Haze and makes Bounty Hunter an easy target for Slardar and his team.

* The brutal physical damage of Slithereen Crush and Bash of the Deep can quickly remove Void Spirit's shield and stun him for a while.
* Corrosive Haze provides vision of Void Spirit while he is running away and Guardian Sprint allows Slardar to quickly close the gap

* 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.

* Corrosive Haze and Bash of the Deep will make short work of Huskar's low armor, even if Slardar is alone.

* 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 makes him particularly vulnerable to Legion Commander's high physical damage.

* Nyx Assassin's Vendetta can be revealed easily by Corrosive Haze

Additional:
* Corrosive Haze hinders Nyx Assassin's ganking attempts with Vendetta, as well as reducing his armor and make him very vulnerable due to his low health pool.

* Duel's long duration prevents Nyx Assassin escaping from Vendetta. With Aghanim's Scepter she can also bypasses Spiked Carapace.

* Crystal Maiden's already low armor and easily interruptible ultimate, Freezing Field can make Slardar her worst nightmare. Crystal Maiden also often builds Glimmer Cape which is revealed by Corrosive Haze.

* 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.

* Corrosive Haze works much like Track, giving the enemy team vision over Riki. While it doesn't give a movement speed bonus, it instead melts Riki's armor and Slardar can use Guardian Sprint to catch up to him.
Additional:
* Corrosive Haze makes Riki completely vulnerable to Slardar and his allies, as Riki has no easy way of dispelling it.
* Slardar's physical damage with Slithereen Crush and Bash of the Deep amplified by Corrosive Haze can easily kill Riki.

* 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).

* Slardar can attack through Plague Wards and gaining Bash of the Deep charges.

* 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.

* Corrosive Haze helps counteract Tiny's bonus armor from Grow, as well as giving true sight, countering Shadow Blade as a common item on Tiny.

* Legion Commander's spells are relatively useless to Rubick, as Duel isn't suitable for someone as squishy as Rubick.
* Press the Attack can be useful, but its high mana cost will leave you with little mana.
* Overwhelming Odds only does damage and gives a movement speed bonus, Rubick can't do much with the extra move speed.
* Generally, you will be a prime target for Legion Commander's Duels, as Rubick is relatively frail.

* Shadow Fiend, a normal Shadow Blade builder often relies on its invisibility to escape fights. Corrosive Haze reveals Shadow Fiend and also weakens his already low armor.

* Corrosive Haze followed by Slithereen Crush takes advantage of Alchemist's main weakness, being physical damage before he has the change to improve his surviability with items.
* Bash of the Deep will deal lots of damage during the laning phase.
Additional:
* Alchemist has a low starting armor and a low agility growth, which translates to a low armor growth . And since it is very uncommon for Alchemist to get straight to Assault Cuirass, or Shiva's Guard, Corrosive Haze makes him too vulnerable to physical damage, even with the hp regeneration of Chemical Rage

* Duels prevents Queen of Pain from using Blink, which may force her to purchase a Linken's Sphere or go for the spell block talent.
* 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.

* 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.

* Press the Attack dispels Flaming Lasso.
* Batrider is unlikely to win a Duel in any stage of the game.

* 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.

* Chen's fragility 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.
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.

* Drow Ranger's low mobility and lack of defensive abilities makes 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.

* 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.
Additional:
* 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.

* Legion Commander's Overwhelming Odds works similar to Echo Slam but with less damage.

* Heroes with detection: Bounty Hunter, Disruptor, Razor, Slardar, Spectre, Spirit Breaker

* Slardar's level 25 talent makes Corrosive Haze undispellable, thus providing his allies a vision to Slark.

* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen

* Heroes with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, Lich, Techies, Rubick

* Heroes with high physical damage can damage Lifestealer more than he can heal: Bristleback, Clinkz, Luna,Shadow Fiend, Slardar

* 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.

* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: Venomancer, Earth Spirit, Ogre Magi

* Heroes with long lockdowns: Shadow Shaman, Legion Commander.

* Invoker's Ghost Walk can be countered, however, Invoker could also use abilities like Tornado or Ice Wall to escape by other means.

* Heroes who can provide True Sight are always credible threats: Slardar, Bounty Hunter, especially Zeus since his Lightning Bolt provides True Sight without the need to detect her beforehand to apply the debuff. So even a late-coming Zeus can easily scout a large area to reveal her, and she cannot purge herself from his sight with the dispel talent.

* Heroes with low health will die easily during Duels, and can be farmed for damage in the early game: Crystal Maiden, Lich, Techies, Rubick

* Heroes who rely on summons will see them destroyed easily by Overwhelming Odds: Lycan, Arc Warden, Warlock, Chen

* Heroes rely on their debuff to control the opponent will have a hard time against Press the Attack: Venomancer, Earth Spirit, Ogre Magi

* Heroes that can protect or dispel stunned allies such as Legion Commander, Outworld Devourer, Shadow Demon and Oracle can reduce the effectiveness of Sacred Arrow.

* Heroes with spells that negate invisibility such as Bounty Hunter, Zeus and Slardar prevent her from saving her allies with Moonlight Shadow.

* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, Chaos Knight, Terrorblade, Naga Siren

* Slardar's Slithereen Crush allows him to stun Spectre and illusions, and Corrosive Haze prevents her from juking with Spectral Dagger.

* Press the Attack can dispel the blind from Blinding Light from a hero.
* Duel can be used to instantly take Keeper of the Light out of a team-fight.

* Corrosive Haze grants vision of Monkey King, even when he is in the trees.

* Duel's long duration prevents Terrorblade from swapping his health with Sunder.
* Overwhelming Odds deals high damage to Terrorblade's illusions.

* Duel pierces spell immunity and forces him to attack Legion Commander, making him unable to use Omnislash.

* Corrosive Haze will reveal Treant Protector even when he is under the effects of Nature's Guise.

* Overwhelming Odds deals high damage to Phantom Lancer's illusions.
* Duel's long duration prevents Phantom Lancer from using Doppelganger.

* 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.

* Heroes who can dispel will be able to remove Shadow Poison before Shadow Demon can build up a big stack, or remove Soul Catcher's debuff to instantly bring the health of affected heroes back to a considerable amount: Abaddon, Slark, Legion Commander, Oracle.

* Duel is very effective against Io due to its low health and armor.

* Pudge, Legion Commander and Axe will make the match a living hell for you, since they are known for surprise attacks from the fog and quickly killing low HP heroes. They can also interrupt your channeling, Legion being especially problematic, as she can use Press the Attack on an ally who is hexed as well.