* Nethertoxin breaks the damage block from Bulwark.
* Poison Attack and Viper Strike's slows make it difficult for Mars to contribute to fights due to his low mobility.
Additional:
* Nethertoxin disables Bulwark entirely, making Mars far less tanky. Using Nethertoxin inside Arena of Blood may discourage enemies from following up with Mars' initiation.
* Rod of Atos is currently common on Viper and keeps Mars in position long enough to be killed.
* Beware that Viper is not very tanky earlier in the game, so positioning against Mars is important since a well-timed Spear of Mars can be the end of Viper.

* Burning Spear's magical damage is very troublesome for Mars in the laning stage.
* Life Break's percentage-based magical damage bypasses Bulwark, and can also be used to jump in or out of Arena Of Blood.

* The damage over time from Viper's Poison Attack and Viper Strike rapidly wear down Refraction charges, allowing Templar Assassin to be damaged. Additionally, Corrosive Skin causes her attacks to apply damage overtime on her as well.
* Nethertoxin is a big threat to Templar Assassin. Her initially low range making it very hard to deal against Nethertoxin in the laning phase. At any stage of the game, a Nethertoxin can always force her to undo her Meld.
Additional:
* All of Viper's abilities quickly burn through Refraction charges.
* Templar Assassin's short range, aside from Psi Blades' spill damage, makes her vulnerable to Poison Attack harassment.
* Templar Assassin traditionally forgoes health and armor items for damage. Outside of Black King Bar, Viper will almost always be able to kill her when Refraction is down.

* Huskar's burn damage from Burning Spear is incredibly strong against Templar Assassin as it completely cancels out her Refraction from the burning over time which results in making her very vulnerable to ganks and harassments, and in turn forcing her out of the lane.

* Corrosive Skin severely reduces Zeus's damage output throughout the game.
* During the laning stage, Viper can abuse Zeus' reliance on spells by hugging the creep wave. Zeus will take constant damage over time from Corrosive Skin unless he drives Viper from the lane or returns to farming in his absence.
* Prior to buying Blink Dagger or Force Staff, Zeus is fragile and possesses low mobility. Any of Viper's numerous slows can set up an easy kill.
Additional:
* Corrosive Skin counters Zeus in lane by canceling the effects of Clarity as Zeus relies on Arc Lightning to farm and secure last hits.
* Corrosive Skin also increases Viper's magic resistance to shrug off Zeus's magical nukes.
* Nethertoxin breaks Static Field.
* Due to Zeus' poor mobility, Viper Strike will cripple Zeus and will allow Viper and his teammates to land a lot of attacks.

* Huskar's Burning Spears chip through his low health pool quickly.Consequently, he is forced to either invest on health regen or abandon the lane.
* Reliant on magic damage, there is little he can do against Huskar.
* Huskar will usually kill him if he gets Life Break off,given Zeus' poor mobility.

* Corrosive Skin gives Viper additional resistance to Phoenix's magical damage, and since they deal damage over time, Phoenix would be constantly afflicted by his passive's own debuff, making him not an ideal target for Phoenix's harassment. Phoenix's abilities also constantly drain its own health away, becoming more vulnerable to Poison Attack.

* Huskar's high attack speed can counteract Fire Spirits, and easily destroy the Supernova.
Additional:
* Berserker's Blood will let Huskar easily face down a Supernova with increased attack speed.
* Icarus Dive may not be an easy escape from Huskar either as he can chase Phoenix during it with Life Break if Huskar times it right.

* Poison Attack and Viper Strike allowing to kite and slow Earthshaker significally, putting Blink Dagger on cooldown and preventing him from initiating or re-initiating.
* Nethertoxin breaks Aftershock. The silence from Level 25 talent also prevents Earthshaker from initiating or re-initiating.
Additional:
* Being a melee hero, Earthshaker's movement is liable to suppression by Poison Attack and Viper Strike.
* Earthshaker's kit, with the exception of Enchant Totem, deals magic damage. Corrosive Skin effectively blunts his killing potential with a standard Blink combo among other things.
* Nethertoxin disables Aftershock, which removes the stun and bonus damage from Enchant Totem and Echo Slam.

* Earthshaker's stuns will rarely save him once Huskar has initiated on him with Life Break.
* A full initiation combo will not kill Huskar, only lower his health and increase his attack speed.

* Viper's Poison Attack and Viper Strike that can slow Razor, and is one of the few heroes that can keep him immobile.
* Altogether, Viper's skills reduce Razor's attack speed, heavily reducing the benefit of the damage drain from Static Link.
Additional:
* Storm Surge is counteracted by Nethertoxin, leaving Razor without faster MS.
* Static Link's damage drain doesn't bother Viper a lot as most of his early to mid game damage is magical.

* Life Break along with Burning Spear can quickly kill Razor before Static Link steals enough damage for Razor to take down Huskar.
* Berserker's Blood can make stealing Huskar's damage and using it against him somewhat dangerous, as Huskar will be able to inflict more and more Burning Spears rapidly.

* In the early game, a Dragon Knight without Black King Bar is basically defenseless against Viper.
* Viper can harass Dragon Knight at any time with his Poison Attack.
* Corrosive Skin reduces damage from Dragon Fire and inflicts damage to him.
* Nethertoxin disables Dragon Blood, negating his main survivability.
* Viper Strike and Poison Attack can severely slow him down even with his Elder Dragon Form.
Additional:
* Dragon Knight is easily harassed by Poison Attack after the laning stage ends.
* Corrosive Skin protects Viper from Breathe Fire and returns damage.
* Nethertoxin mitigates Dragon Blood, Dragon's Knight main source of armor and health regeneration.
* Between Poison Attack and Viper Strike, Viper can keep Dragon Knight permanently slowed even in Elder Dragon Form.

* Huskar can burn down Dragon Knight's health quickly during the early to mid game, but is not as effective during the late game. However, Life Break remains a constant threat due to the slow and percentage-based damage.

Additional:
* Huskar can negate Dragon Knight's passive with multiple trades of Burning Spear.

* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.

* Since Tidebringer has a 4 second cooldown, Kunkka has little availability to manfight Huskar.

* Nethertoxin prevents the buildup of Jingu Mastery stacks.
* Viper's poison magical damage-over-time stops Monkey King from using Tree Dance. It also ignores the extra armor bestowed by Wukong's Command.
Additional:
* Nethertoxin prevents the buildup of Jingu Mastery stacks.
* Monkey King's high base movement speed is of little worth against the array of slows Viper possesses.
* All of Viper's magical damage over time stops Monkey King from using Tree Dance. It also ignores the extra armor bestowed by Wukong's Command.

* Burning Spears can put Monkey King's Tree Dance on cooldown.

* Corrosive Skin means Viper can often outlast Venomancer in a battle of attrition.
* Venomancer has no mobility without items, which makes him vulnerable to constant slows.

* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: Lich, Crystal Maiden, Silencer, Keeper of the Light, Venomancer, etc.

Additional:
* Huskar can easily regenerate lost health from DoT spells through Berserker's Blood rendering them ineffective
* Venomancer has little armor and mobility, and rarely builds Linken's Sphere, so he is quite vulnerable to Life Break.

* Any hero who can survive Magnus's initiations and manfight him: Huskar, Faceless Void, Weaver, Abaddon, Troll Warlord, Alchemist, Dragon Knight, Night Stalker, Viper.

Additional:
* Most of Magnus' abilities except Empower will trigger damage through Corrosive Skin.
* Poison Attack and Viper Strike can slow Magnus during Skewer, as well as putting his Blink Dagger on cooldown, preventing him from initiating or re-initiating.

* Magnus cannot manfight Huskar even with Empower, Berserker's Blood's high attack speed and health regeneration, combined with Huskar's high health and Burning Spear stacks will allow Huskar to kill Magnus before he can kill him.
* From a safe distance, Huskar can surprise and counter Magnus's initiation with Life Break and Burning Spear.
* Burning Spear also deals damage over time, disabling Blink Dagger and preventing him from initiating or escaping.

* Viper's poison abilities can slow Bounty Hunter's movement speed and allows to chase him with True Sight items.
* Nethertoxin can break Jinada, and the silence from level 25 prevents Bounty Hunter from using all of his spells.

* Huskar with Life Break
* 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.

* Nethertoxin cuts off Gravekeeper's Cloak, Visage's primary defense mechanism.
* Viper can ignore Grave Chill's attack speed slow with his magic damage output.
Additional:
* Since Visage is a slow hero, Viper can easily kite him with Poison Attack and Viper Strike while successfully chipping away at Gravekeeper's Cloak.
* Nethertoxin removes all layers of Gravekeeper's Cloak, leaving Visage exposed.
* Corrosive Skin makes Viper highly resistant to Soul Assumption.

* Heroes with damage over time abilities can quickly eat through Gravekeeper's Cloak charges like Huskar, Jakiro and Queen of Pain.

* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.

* Heroes who can take advantage of Gods Strength being on cooldown are also not great matchups, such as Templar Assassin, Morphling and Huskar.

* Heroes who can easily harass Crystal Maiden out of lane in the early game (Clinkz, Viper) can prevent Crystal Maiden from being able to level effectively, and can ultimately slow down her level 6, 12, and 18 to a point where enemy carries already have items to address her ultimate.

* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: Lich, Crystal Maiden, Silencer, Keeper of the Light, Venomancer, etc.

* Nethertoxin breaks Sniper's passives.
* Viper Strike together with Poison Attack can slow Sniper and tears through his low health and mobility.

* Nethertoxin prevents Timbersaw from gaining stacks on Reactive Armor.

* Nethertoxin breaks both Necromastery and Presence of the Dark Lord, reducing his damage massively.
* Corrosive Skin gives Viper bonus Magic Resistance against Shadowraze and Requiem of Souls.
* Viper can easily take advantage of Shadow Fiend's lack of escape and mobility spells with Viper Strike and Poison Attack. Poison Attack also serves as a great way to harass Shadow Fiend.

* Poison Attack makes it hard for Void Spirit to lane against him.
* Corrosive Skin reduces the magical damage from Void Spirit's spells.

* Tiny has low movement speed and attack speed, making him vulnerable to Viper's slows.
* Corrosive Skin provides magic resistance to lower Tiny's magic burst damage.

* Nethertoxin breaks Multicast.
* Corrosive Skin minimizes the damage from Ignite and Fireblast.

* Corrosive Skin minimizes the damage Viper takes from all of Disruptor's skills.

* Ember Spirit does minimal damage to Huskar until the very late game.

* Corrosive Skin will protect Viper from Techies' magical damage.
* Even though Reactive Tazer will disarm Viper if he attacks Techies with Poison Attack, he does lots of damage with his other abilities that can still kill Techies.

* Nethertoxin cancels out Kraken Shell and stops the hard dispel from passively activating, preventing Tidehunter from functioning as a frontline tank.
* Anchor Smash is mostly irrelevant against a ranged hero.
* Tidehunter relies on the threat of Ravage, which has an obscenely long cooldown. Viper can exploit the downtime with his short cooldowns.

* Clockwerk cannot go head-to-head with Huskar in Power Cogs, as Berserker's Blood and Life Break will destroy him faster than the other way around.
Additional:
* Clockwerk's abilities cannot handle Huskar in a one-on-one fight, even if he gets the jump on him.

* Corrosive Skin minimizes the damage from Impale and Mana Burn.
* Nyx Assassin cannot survive several poison damage-over-time, even Spiked Carapace is activated.

* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker.

* Nethertoxin disables Dawnbreaker's Luminosity|Dawnbreaker. Since she's a melee hero, she needs to close gap to attack and Nethertoxin will be bad for her since she cannot heal.
* Viper Strike and Poison Attack will severely slow her down and combined with Nethertoxin, it will be her death sentence (unless her Celestial Hammer or Solar Guardian are off cooldown). Besides that, chasing her down will be easy due to the slow.

* Life Break and Burning Spear usually kills Gyrocopter before he can do much damage to Huskar.
* Inner Fire applies a disarm on all enemies, which can be a hindrance to Gyrocopter.

* Life Break closes the distance between Huskar and Drow Ranger, dealing large amounts of damage and disabling Marksmanship.
* Berserker's Blood and Burning Spear allow Huskar to beat Drow Ranger directly and pile on damage.

* Nethertoxin disable passives, negating Spectre's damage and survivability by removing both Dispersion and Desolate.
* Due to Haunt and Radiance's burn, Spectre is heavily susceptible to being persistently slowed and damaged by Corrosive Skin without even directly attacking Viper.
* Poison Attack and Viper Strike further slow Spectre's movement speed to a crawl, while his improved magic resistance means he can easily shrug off Radiance's burn.
Additional:
* Nethertoxin disables Desolate and Dispersion, leaving Spectre with far less damage output and damage mitigation in engagements.
* Spectre is one of the weakest heroes at early levels. Viper can stifle her farm with early fights before Spectre purchases any major items.

* Viper's Nethertoxin disables Cloak and Dagger, negating Riki's invisibility and much of his damage. It also makes him more vulnerable to magic damage, which does not go well with Riki's low health pool. With the talent applied, he can't even blink to safety or hide with Tricks of the Trade.
* Corrosive Skin makes it hard for Riki to chase Viper and attack him due to the attack speed slow.
* Viper Strike stays on Riki even after he goes invisible.
* Poison Attack makes it risky for Riki to get last hits and can make the laning phase difficult for him.

* Nethertoxin prevents the lifesteal from Ransack.
* Meepo and his clones have a lack of magic resistance, so they're vulnerable to Poison Attack & Viper Strike directed onto one clone.

* Certain heroes can mess up with Pangolier's positioning and timing (especially if he intends to use Rolling Thunder during combat): Vengeful Spirit, Keeper of the Light, Huskar, Dark Seer

* Bristleback, Centaur Warrunner, Spirit Breaker, Pudge, Huskar: These heroes are too tanky for Puck to burst down. Also, all of them have spells which can deal with and shut Puck down reliably.

* Heroes with spell immunity: Juggernaut, Pangolier, Huskar.

* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: Lich, Crystal Maiden, Silencer, Keeper of the Light, Venomancer, etc.

Additional:
* Lich is going to have a hard time nuking Huskar because of his high health regeneration from Berserker's Blood.
* Lich is a squishy support without an escape mechanism, making Lich an easy kill thanks to Life Break and Burning Spear.
* Once Huskar has Armlet of Mordiggian, even a maxed out Frost Blast will struggle to finish Huskar off.

* Heroes with Break abilities will prevent Slark from regenerating and gaining Essence Shift stacks: Viper, Shadow Demon, etc.

Additional:
* Nethertoxin negates Essence Shift and the regeneration aspect of Shadow Dance.
* Dark Pact doesn't mean a lot against Viper's ubiquitous slows.
* Viper becomes a relevant presence in team fights before Slark can procure his standard items (e.g. Shadow Blade).

* Hand of God has a long cooldown, so damage over time spells can be hazardous for Chen, forcing him to use it prematurely: Jakiro, Venomancer, Viper, Dazzle, Phoenix.

* Heroes with damage-increasing passive abilities, such as Viper and Riki, will usually kill Silencer in a short time before he even has time to set up his abilities.

* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: Lich, Crystal Maiden, Silencer, Keeper of the Light, Venomancer, etc.

* Huskar's huge damage output and attack speed can get rid of Undying and Tombstone quickly.

* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.

* Heroes who can harass Omniknight out of lane will keep him weak in the mid game: Viper, Venomancer, Clinkz.

* Sprout will not protect Nature's Prophet from Huskar if he has already locked on with Life Break.
* Even a farmed Nature's Prophet is usually not durable enough to fight Huskar alone.

* The slow applied from Corrosive Skin offsets the movement speed bonus granted by Scorched Earth and the tick-based damage from Infernal Blade and Doom will continually slow Doom down. This allows Viper, much like Sniper, to 'kite' Doom and keep him at a safe distance between the two. Additionally, Corrosive Skin applies an attack-speed slow which is fairly crippling to a hero such as Doom that, naturally, has a high base attack-time, poor agility gain and builds little attack-speed items.
* Since Doom does not disable auto-cast abilities, Viper's Poison Attack will continue to work. Doom may find it hard to close the distance between himself and Viper, and thusly difficult to effectively lockdown and continually deal damage through his abilities.

* Nethertoxin disables Vengeance Aura.
* Vengeful Spirit has no mobility spells aside from Nether Swap, which Viper can take advantage of with his slows.
* Viper can easily bully Vengeful Spirit out of a lane with Poison Attack.
Additional:
* Nethertoxin prevents the attack damage bonus from Vengeance Aura and the components of Nether Swap.
* Both Magic Missile and Wave of Terror are counteracted by Corrosive Skin, making Vengeful Spirit's fighting harder against Viper.

* Berserker's Blood works proportionate to lost health, but Huskar has a decent health pool, and the attack speed granted from Berserker's Blood powers him up.
* Skywrath Mage's armor and agility gain is very low so Huskar can outdamage him or take Skywrath Mage down with him.

* Nethertoxin prevents buildup of Fiery Soul stacks.
* Corrosive Skin provides magic resistance against Lina's spells.
* Poison Attack and Viper Strike can burn away Lina's small health pool.

* Because Poison Attack has no cooldown, Aphotic Shield is ineffective as a hard dispel.
* Nethertoxin prevents Borrowed Time from activating passively and blocks Curse of Avernus

* Viper's skill set makes him an effective early game ganker against Anti-Mage before he is sufficiently farmed.
* Viper's Corrosive Skin and low mana pool causes him to take little damage from Mana Void.
* Nethertoxin disables Mana Break and Counterspell, weakening both his offense and defense.

* Huskar does not need any mana to fight Anti-Mage as most of his skills cost HP instead. He is good counter to take away Anti-mage's farm in early to mid game. Huskar, however, struggle to kill Anti-Mage in the late game. So it is a good idea to finish the game early before Anti-Mage can farm up.

Additional:
* Huskar is not very reliant on mana to cast his spells, therefore, Mana Break is not very effective against him.
* Huskar also has low mana pool, he will take less damage once his mana pool is completely depleted. Mana Void is also ineffective against him.
* Huskar comes online earlier than Anti-Mage, and can take over the game before Anti-Mage can farm up.

* Nethertoxin disables Bristleback's passive.
* Viper Strike and Poison Attack slow down Bristleback's movement speed so he's unable to get out from Nethertoxin.
Additional:
* Nethertoxin disables Bristleback and prevents Warpath from building stacks. Besides losing his defensive passive, Bristleback also loses his ability to build up damage over lengthy battles.
* Viper can perpetually kite Bristleback with Poison Attack and Viper Strike.

* Heroes that can slow Charge of Darkness by a huge amount: Venomancer, Viper, Dazzle, Arc WardenLion

* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: Lich, Crystal Maiden, Silencer, Keeper of the Light, Venomancer, etc.

* Poison Attack and Viper Strike slows Axe significantly, and puts his Blink Dagger on cooldown, preventing him from initiating.
* Nethertoxin can break Counter Helix.
Additional:
* Nethertoxin prevents Counter Helix from triggering, which significantly lowers Axe's damage output in the early to mid game.
* Viper's various slows and damage over time prevents Axe from initiating as well as putting his Blink Dagger on cooldown.

* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.

* Corrosive Skin minimizes the damage Viper takes from all of Ancient Apparition's abilities.
* Ancient Apparition's slow movement speed, squishy nature, and lack of escape abilities can easily be taken advantage of through Poison Attack and Viper Strike.

* Viper does large amounts of magic damage over time, meaning that if a Necrophos uses Ghost Shroud, Viper's abilities will greatly reduce Necrophos survivability, and may actually kill him.
* By the same token, Viper can use his Viper Strike on Necrophos if he attempts to heal himself with Ghost Shroud, and depending on any other effects Necrophos may have from him, (IE:Poison Attack,Corrosive Skin), Viper can often kill Necrophos while he is in his Ghost Shroud.
* Viper's Corrosive Skin helps him take reduced damage from all of Nercophos spells that deal magical damage, which is Necrophos's only source of damage.
Additional:
* Nethertoxin prevents Heartstopper Aura from dealing damage or healing Necrophos.
* Viper's magic damage is amplified whenever Ghost Shroud is used.
* Corrosive Skin makes Viper tankier against Death Pulse and Reaper's Scythe.

* Nethertoxin breaks Fury Swipes, making Viper a decent counter to Ursa in a laning stage.
* Viper Strike is a strong, undispellable slow, making it much easier to kite Ursa for everyone.