* Heroes that build Diffusal Blade or can fit it well into their item build will also make Medusa much less tanky: Riki, Naga Siren, Terrorblade, Juggernaut, Spectre, Slark,Drow Ranger.

* Medusa cannot chase Slark in any way and has no disable beyond her ultimate, making her unable to stop him getting away and regenerating before coming back to finish her off.
* Essence Shift particularly removes 1 intelligence point per hit, thus lowering Medusa's mana pool's cap and leaving her much more vulnerable in prolonged fights.
Additional:
* Medusa is especially vulnerable to Essence Shift, as both strength and intelligence contribute to her effective HP, while agility contributes to her damage.
* Dark Pact when timed right can be used to dispel Stone Gaze right after it petrifies Slark, allowing him to keep attacking Medusa throughout the duration.

* Dark Pact can dispel Venomous Gale and Poison Sting.
* Shadow Dance allows Slark heightened regeneration when out of vision making DoTs effects less threatening.

* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.

* Heroes with escaping and disjointing abilities can be good against Juggernaut:Anti-Mage Riki, Queen of Pain, Puck, Storm Spirit, Ember Spirit, Slark etc.

Additional:
* Blade Fury does not offer any protections against Essence Shift, as it can go through spell immunity and reduces attribute.
* Slark can pounce away from Juggernaut and he cannot prevent or chase slark.
* Shadow Dance prevent Juggernaut from using Omnislash altogether, while regen himself at a higher rate. Slark can freely hit juggernaut without any fears of retaliation.

* Drow Ranger can use Gust to push back Juggernaut before he can get in range to use Omnislash or Blade Fury.

* Pounce prevents Anti-Mage from using Blink, and lets him disengage from Anti-Mage if needed.
* Essence Shift allows Slark to permanently steal agility from Anti-Mage.
* Shadow Dance stops Anti-Mage from being able to fight back in a slippery situation.

* None of Anti-Mage's skills are that effective against Drow Ranger. Gust prevents him from Blinking in or out, Counterspell is totally useless against Drow's physical damage, and as she usually doesn't have a high mana pool, Mana Break and Mana Void don't do much either.
* Be careful however that Anti-Mage may eventually farm enough to Blink on top of you and kill you straight away, considering you have no natural tools to escape from him.

* Heroes with blink or movement abilities, which are disabled by Pounce's leash: Anti-Mage, Earth Spirit, Faceless Void, Magnus, Mirana, Monkey King, Morphling, Pangolier, Phantom Assassin, Phoenix, Puck, Queen of Pain, Riki, Sand King, Spirit Breaker, Timbersaw, Tusk.

Additional:
* Dark Pact easily purges away both slow and disarm effect from Lucky Shot.
* With Pounce now applying leash to the target, Pangolier is helpless against Slark since both his Swashbuckle and Rolling Thunder will be disabled. Pounce also help Slark to easily escape from Rolling Thunder.

* Powerful physical hitters that can destroy Pangolier during his rolling from afar: Drow Ranger, Sniper, Templar Assassin, Arc Warden

* With 4 active abilities, Shadow Shaman is weak against silencing foes such as silencer, Drow Ranger and Death Prophet.

* Nyx Assassin, Bounty Hunter and Slark can all sneak up and kill you, Nyx being particularly deadly. Watch Slark carefully, as he can break either (but not both unless you are making a mistake) of your disables, with Dark Pact and leap out of a serpent ward ring. These heroes, however, rely heavily on escape and are themselves not very durable and none of them can survive a full lockdown with Mass Serpent Ward. Having Sentry Wards can turn you from prey to predator.

* Essence Shift allows Slark to hit bristleback freely whether on the front or back, stealing attributes and make bristleback much less tanky.
* Pounce can be used to disengage and recover loss HP with his ultimate passive, and can return to fight in a short period while bristleback is already injured and got some of his attributes stolen.
* Dark Pact makes it near impossible to keep Viscous Nasal Goo debuff on slark.
* Although Dark Pact cannot dispel Quill Spray, means Slark will still receive quill stack damage even if he uses Shadow Dance before.
* Slark builds Silver Edge in almost every game, an item that greatly counter birstleback.

* Dragon Knight has no built-in disengage from Frost Arrows, and Marksmanship procs ignore base armor, bypassing Dragon Knight’s durability for the most part, making Drow one of the few heroes that can deal enough sustained damage to solo kill Dragon Knight.
* With Aghanim's Shard, Frost Arrows also apply hypothermia stacks, reducing her target’s regen, which is especially potent against tanks like Dragon Knight. (A similar effect can also be achieved with an Eye of Skadi)

* Dark Pact, if timed correctly, can dispel Wraithfire Blast's stun and slow.
* Since Wraith King has a lot of health and multiple lives, Slark can keep gaining Essence Shift stacks, increasing armor, damage, and attack speed and can beat down Wraith King twice.
* Slark sometimes carries Diffusal Blade to burn mana as an attempt to shut down Reincarnation.
* Because Wraith King has no AoE abilities, Shadow Dance is particularly useful against Wraith King.

* Dark Pact can dispel Flaming Lasso if is used in anticipation, but a Blink initiation from fog can catch the Slark off guard.
* Slark can also take off any Sticky Napalm stacks with Dark Pact in lane.
Additional:
* Sticky Napalm is dispelled by Dark Pact, without it, Batrider will not be as threatening
* Shadow Dance's passive can inform Slark when he's under enemy vision, meaning it'll be very hard to catch Slark off-guard with Flaming Lasso.
* Flaming Lasso is dispelled by Dark Pact. Its casting can be prevented with Shadow Dance or Depth Shroud (it requires Aghanim's Shard).

* Shadow Dance allows Slark to not be targeted by Unstable Concoction, making Alchemist stun himself and making himself vulnerable to the enemy.
* Dark Pact also allows him to just purge off the stun if timed correctly.
* Essence Shift will steal stats over long durations at a time should Alchemist lack the damage to kill Slark.

* A well-timed Gust will prevent Rubick from casting abilities from Spell Steal, and his lack of capabilities and low health pool usually dies very quickly.
* Drow Ranger can dispel Fade Bolt's reduction debuff with Manta Style.

* Gust can hit Dark Willow beyond a defensive Bramble Maze, and before she gets close enough to hit Drow Ranger with Bedlam.
* Drow Ranger's long range allows her to hit Dark Willow's team without venturing into her Bramble Maze.

* Dark Pact dispels Ignite's slow and Fireblast's stun.
* Shadow Dance allows Slark to regenerate HP, even when he is affected by Ignite and Fireblast.

* Slark's Pounce can be used to dodge Hoodwink's abilities or lock her down.
* Shadow Dance makes Slark unhittable from Acorn Shot.
* Dark Pact removes all slows from Hoodwink's abilities.
* Hoodwink's already low health output is a great target for Slark's Essence Shift.

* Arctic Burn and Splinter Blast debuffs are dispellable with Dark Pact. Arctic Burn is also no escape against Pounce.
* Cold Embrace gives Slark free Essence Shift stacks.
* However, Essence Shift works against allies, and Slark's low health pool means that if he's the target for Winter's Curse, he will go down very quickly.

* A well-timed Gust will prevent Weaver from escaping, and a silenced Weaver usually dies very quickly.
* Precision Aura easily removes The Swarm beetles or counteracted by Shadow Blade/Silver Edge.
Additional:
* A well-timed Gust followed by Frost Arrows will prevent Weaver from escaping with Shukuchi. A Weaver silenced for more than 3 seconds usually dies very quickly.
* Due to her high attack speed, Drow Ranger can easily kill The Swarm beetles.

* Every hero that can withstand or prevent Eclipse at level 7: Juggernaut, Riki, Clockwerk, Drow Ranger, Abaddon, Faceless Void, Weaver, Outworld Destroyer.

* Shadow Dance prevents Luna from damaging Slark, and together with Shadow Blade he can kite her or escape.
* Luna has no way to escape from Pounce's leash.
* For the same reasons, Slark makes a very powerful ally for Luna when they are in the same team.
Additional:
* Luna's lack of mobility and escape abilities makes her easily to gank for Slark.
* Shadow Dance helps avoid all the damage from Eclipse.

* Shadow Dance allows Slark to attack Lifestealer for its duration without any way for Lifestealer to fight back.
* Slark commonly buys a Silver Edge, which can break Lifestealer's Feast, severely diminishing his damage output and lifesteal.

* Gust can shut down most of Dawnbreaker's abilities, rendering her useless.
* Frost Arrows followed by a high attack speed, makes it hard for Dawnbreaker to escape.

* If Slark sees the Sacred Arrow before it hits him, he can use Dark Pact to remove it a moment later.
* Pounce prevents Mirana from escaping with Leap.
* Slark can survive Mirana's Aghanim's Scepter​ combo with Shadow Dance.

* Gust prevents Mirana from escaping away from Leap and Moonlight Shadow before she builds defensive items.
* On the other hand, Mirana can Leap or close the gap with Moonlight Shadow to disable Drow Ranger's Marksmanship bonus.

* 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.

* Dark Pact dispels debuffs from Gush, Anchor Smash and even Ravage if timed correctly.
* Kraken Shell cannot restore attributes stolen by Essence Shift or dispel the leash if he gets Pounced.

* Slark's Dark Pact allows him to dispel Silencer's debuffs.
* Against a carry Silencer, Essence Shift will lower damage from both Glaives of Wisdom and his basic attack.

* Heroes who rely on passive abilities and attacks, such as Drow Ranger, Wraith King, and Lone Druid, can render Silencer useless. But remember that a smart Silencer will most likely buy Silver Edge to counter this if he is played as carry.

* Pounce also stops Nature's Prophet's Teleportation.

* Heroes with blink or movement abilities, which are disabled by Pounce's leash: Anti-Mage, Earth Spirit, Faceless Void, Magnus, Mirana, Monkey King, Morphling, Pangolier, Phantom Assassin, Phoenix, Puck, Queen of Pain, Riki, Sand King, Spirit Breaker, Timbersaw, Tusk.

Additional:
* Pounce's root prevents Earth Spirit from using Rolling Boulder to escape, making it easier for Slark to shut him down especially in the laning phase.

* Heroes with forced movement abilities or non-interrupting forced movement, such as Lion, Drow Ranger, Magnus, Mars, as they can cancel blast-off mid air, removing his ability to initiate or escape.

* Windranger heavily relies on her abilities for any form of tactical advantage and damage. A well timed silence will make her useless: Puck,Silencer, Death Prophet, Skywrath Mage, Drow Ranger, Earth Spirit, Grimstroke.

* Heroes with silence: Death Prophet, Riki, Drow Ranger.

* Heroes with strong dispels can remove Primal Roar's stun: Abaddon, Slark, Oracle.

* Heroes with blink or movement abilities, which are disabled by Pounce's leash: Anti-Mage, Earth Spirit, Faceless Void, Magnus, Mirana, Monkey King, Morphling, Pangolier, Phantom Assassin, Phoenix, Puck, Queen of Pain, Riki, Sand King, Spirit Breaker, Timbersaw, Tusk.

* As a spellcaster, silences will nullify him entirely. Some notable examples are Death Prophet, Drow Ranger, Bloodseeker, Disruptor and many others.
* Doom, as usual, fits this description nicely.

* Zeus can deal a huge amount of damage, but he lacks defensive abilities, such as good mobility or resistance. Due to that, he doesn't like to be touched by any means. Heroes with higher damage output and good mobility will often get easily near Zeus and trade damage (eventually causing Zeus's downfall). Such Heroes include: Lycan, Slark, Storm Spirit, Spectre and others.

* Slark with Dark Pact
* 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.

* Heroes who have a high mobility (Queen of Pain, Storm Spirit, Slark, etc.).

* Heroes with low health and armor are especially vulnerable to Marksmanship's high damage output: Clinkz, Crystal Maiden.

* Enigma lack 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.

* Marksmanship allows Drow Ranger to pierce Terrorblade's high natural base armor and when upgraded with Aghanim's Scepter, it will allow her to clear Terrorblade's illusions.
* Gust can prevent Terrorblade from from using Sunder.
* Since Terrorblade doesn't like to buy armor items like Assault Cuirass, he will be very vulnerable to Drow Ranger's high physical burst damage.

* Pounce's leash prevents Storm Spirit from using Ball Lightning, making it hard for Storm Spirit to escape a gank from Slark.
* Dark Pact can dispel Orchid Malevolence's Soul Burn.

* Dark Pact can be cast during the cast animation of Light Strike Array and dispel its stun.
* Pounce allows Slark to close the gap to Lina.
* Shadow Dance prevents Lina from killing Slark with her Laguna Blade when his HP gets low.

* Drow Ranger can be difficult to get on top of, thanks to her Frost Arrows and Gust. With these two abilities, Drow Ranger is able to effectively 'kite' Doom and minimize his impact during team fights and laning stage.
* Much of Drow Ranger's effectiveness comes from her passive, which is not disabled by Doom.

* 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.

* Slark is a natural Shadow Blade carrier, which allows Slark to close the gap to Sniper.
* With Essence Shift and Shadow Dance, Slark will easily win a fight against Sniper.
* However, Pounce can be broken with Force Staff or Hurricane Pike.
Additional:
* Sniper hugely lacks mobility and escape abilities so that he is an easy target for ganks from Slark.

* Heroes that can jump on her: Slark, Queen of Pain, Anti-Mage

* Heroes with blink or movement abilities, which are disabled by Pounce's leash: Anti-Mage, Earth Spirit, Faceless Void, Magnus, Mirana, Monkey King, Morphling, Pangolier, Phantom Assassin, Phoenix, Puck, Queen of Pain, Riki, Sand King, Spirit Breaker, Timbersaw, Tusk.

* Heroes that can apply early pressure before Phantom Assassin has farm are massive threats: Axe, Viper, Meepo, Pugna, Slark etc.

Additional:
* Slark's Pounce allows him to close the gap on Phantom Assassin and prevent her from escaping with Phantom Strike.
* As a hero who typically builds Silver Edge, Slark can use it to disable Phantom Assassin's Blur and Coup de Grace, thus taking down her attack evasion and drastically reducing her damage output.
* Because Phantom Assassin is always reliant on critical strikes, Slark will have plenty of time to escape with Pounce, Shadow Dance and Silver Edge (provided that he purchased it already).
* Essence Shift can be very harmful for Phantom Assassin as losing the agility means that her physical damage will be also reduced, which can also weaken Coup de Grace if Slark manages to steal lots of agility from her.
* Overall, any attempt for Phantom Assassin to take down Slark will hurt her more than Slark.

* Heroes with dispels: Legion Commander, Oracle, Slark, Phantom Lancer

* Pounce can easily break Static Link, making it less powerful against him.
* Slark is one of the few heroes who can man fight a Razor, because of Essence Shift.
* Shadow Dance can prevent Razor from killing him and may provide an opportunity to kill Razor due to it preventing Razor from attacking Slark.

* Weak damage but high tick rate or persist in a long time: Slark, Gyrocopter, Queen of Pain, Shadow Shaman (Shackles), Jakiro, Pugna
* Heroes that can quickly deal damage to her, regardless of how weak they are, can easily break through her Refraction:
* Multiple attackers thanks to summoned units or clones: Meepo, Witch Doctor, Lycan, Enigma, Shadow Shaman
* Multiple attackers thanks to illusions: Phantom Lancer, Chaos Knight, Naga Siren (bonus for her Ensnare). Also despite the visual effects, Templar Assassin does not spill damage against illusions or buildings, so she is not a really good hero to clean up illusions.
* Weak damage but high tick rate or persist in a long time: Slark, Gyrocopter, Queen of Pain, Shadow Shaman (Shackles), Jakiro, Pugna

Additional:
* Dark Pact rips through Refraction charges and still steals attributes during Refraction.
* Pounce and Dark Pact will still hit Templar Assassin while she is Melded. Since she cannot move, both abilities will be easy for Slark to land.

* Heroes with blink or movement abilities, which are disabled by Pounce's leash: Anti-Mage, Earth Spirit, Faceless Void, Magnus, Mirana, Monkey King, Morphling, Pangolier, Phantom Assassin, Phoenix, Puck, Queen of Pain, Riki, Sand King, Spirit Breaker, Timbersaw, Tusk.

* Heroes with blink or movement abilities, which are disabled by Pounce's leash: Anti-Mage, Earth Spirit, Faceless Void, Magnus, Mirana, Monkey King, Morphling, Pangolier, Phantom Assassin, Phoenix, Puck, Queen of Pain, Riki, Sand King, Spirit Breaker, Timbersaw, Tusk.

* Dark Seer relies on Surge for most of his mobility, so he's not very vulnerable to slows, but much more to root effects and walls or pseudo-walls such as Disruptor's Kinetic Field or Slark's Pounce.

* Dark Pact dispels Dismember if timed correctly.
* Pounce allows Slark to escape Pudge's Rot once Dismember is over, and allows him to dodge hooks.
* Shadow Dance hides Slark and grants him a high degree of mobility, which can make him a difficult target to hook and also protects him from Pudge's Dismember (including allies with an Aghanim's Shard).

* Heroes with invisibility and high mobility can jump on and focus down Earthshaker before he has a chance to initiate: Clinkz, Slark, Storm Spirit

* Flux is dispelled by Dark Pact.
* Pounce allows Slark to avoid Spark Wraiths.
* Tempest Double allows Slark to build up Essence Shift stacks, especially when it is being used for split pushing.

* Pounce prevents Tinker from blinking away.
* Slark frequently builds Shadow Blade, which allows him to approach Tinker unnoticed. Since Tinker's farming usually covers a significant amount of area on the map, Sentry Wards may not be cost effective.
* Shadow Dance allows Slark to detect both common and unusual wards. Eliminating common ward causes Tinker trouble farming many lanes if he does not know who may be waiting to jump on him. Slark is also uniquely able to identify some of the less common wards used by Tinker, such as those placed on the cliffs at map edges which Tinker uses to give him vision over the trees he uses to hide in.
* Slark's extremely high move speed from Shadow Dance, potentially stacked with Shadow Blade, allows him to easily follow Tinker between lanes, especially if Tinker has pushed the lanes out.
* Dark Pact dispels Laser's blind.