* Heroes with break can disable Untouchable for a while: Doom and Shadow Demon (via Aghanim's Scepter), Viper, Shadow Shaman with Hex Breaks talent.

* Battle Trance and Fervor can help Troll Warlord deal with Encahntress through Untouchable.
Additional:
* Untouchable's attack speed slow is easily remedied by Fervor stacks and Battle Trance.
* Troll Warlord is a natural Silver Edge carrier, disabling Enchantress' Untouchable.

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

* Whirling Axes (Melee)'s blind makes Sven nearly useless in the early game and allows Troll Warlord to take him on comfortably.
* Battle Trance will mean Sven will never take Troll out in a 1vs1 with equal farm.
Additional:
* Berserker's Rage together with Troll Warlord's high attack speed gives Troll a high chance of rooting enemies, which allows Troll Warlord to man-fight Sven.
* Whirling Axes (Melee) provides a 60% miss chance, and the passive armor provided by Berserker's Rage makes Troll resilient to physical damage in early game. Sven's God's Strength is much less effective as a result.
* Beware that Sven can farm much faster than Troll Warlord by stacking ancients and clearing them with Great Cleave.

* 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.

* Any hero with high attack speed will be a threat to Phoenix when it initiates, as they can easily tear down a Supernova, perhaps even while debuffed by Fire Spirits: Juggernaut, Clinkz, Troll Warlord, Beastmaster, Lina.

Additional:
* Due to Fervor and Battle Trance, Troll Warlord is one of the best heroes to deal with Supernova.

* His Poison Attack is very useful against Huskar, since he tends to stay at low health.
* Nethertoxin disables passive skills like Berserker's Blood.
* It is dangerous for Huskar to jump on Viper because Corrosive Skin and Viper Strike with the slowdown of movement and attack speed which usually will be deadly for Huskar.
Additional:
* Nethertoxin disables Berserker's Blood, which Huskar relies upon for attack speed and healing.
* The damage from Burning Spear and Life Break is largely absorbed by Corrosive Skin. It also will return some damage, making it risky to use Burning Spears in the laning stage.
* Because Huskar wants to be on low health for Berserker's Blood, he is particularly vulnerable to Poison Attack.

* Carries that can out damage Huskar will do well against him: Legion Commander, Faceless Void, Troll Warlord, Phantom Assassin.

Additional:
* Whirling Axes (Melee) provides a 60% miss chance, resulting in Huskar's attacks missing a lot of the time if it isn't dispelled.
* Troll Warlord's Fervor ramps up in a very similar way as Huskar's Berserker's Blood: as soon as Huskar has high enough health regeneration, Troll Warlord has a high enough attack speed to negate it.

* 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.

* Troll Warlord can root and deal a lot of damage to a single Meepo while lifestealing through the assault from the other Meepos. Meepo needs expensive items like Ethereal Blade or Heaven's Halberd to be able to fight him.

* 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.

* Generally speaking, Spectre is a strong teamfighter but a weak manfighter. She has no tool to deal with troll warlord once he has his sight locked on her.
* Troll often buys Silver Edge and Monkey King Bar, which greatly countered Spectre's passive and item build (Silver Edge can disable passive while providing some damage, Monkey King Bar provides accuracy to counter Radiance and Butterfly miss chance).
* Black King Bar allows troll to bypass the damage return from Blade mail should Spectre attempts to fight back Troll. However, Black King Bar is generally not very effective against Spectre as her skills can pierce the spell immunity. Still, it offers protection against Blade mail, a common item for Spectre in the mid game.
* Troll has high lifesteal from Battle Trance and Satanic, which help him survive the damage from Desolate should the break duration is over.
* Battle Trance and Fervor mean Spectre will have a hard time fighting troll and cannot take him down, even with equal farm.

* 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.

* Troll Warlord's passive root, high attack speed, and blind from Whirling Axes makes him an exceedingly difficult opponent for Anti-Mage to take down in a one-on-one fight.
* Troll Warlord's low mana causes him to take little damage from Mana Void.
Additional:
* Whirling Axes (Melee) provides a 60% miss chance, preventing Anti-Mage from burning Troll Warlord's small mana pool.
* Troll Warlord's passive root allows him to very effectively fight an Anti-Mage by preventing Anti-Mage from Blinking away. This is even more effective when combined with a Skull Basher or Abyssal Blade.
* Counterspell will do nothing to prevent Troll Warlord's high physical damage.
* Due to Troll Warlord's abysmal base intelligence and intelligence gain, he is one of the worst targets to use Mana Void on.

* 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.

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

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

* Whirling Axes (Melee) makes it hard to land a Coup De Grace.
* Troll Warlord often buys Silver Edge and Monkey King Bar, the items that greatly help against Phantom Assassin's Blur ability.
* Battle Trance completely negates Phantom Assassin's large damage output, preventing Troll Warlord from dying easily. The lifesteal also allows Troll Warlord to restore much of his health.
Additional:
* Troll Warlord can build a Silver Edge or a Monkey King Bar to completely ignore Blur.
* Whirling Axes (Melee) provides a 60% miss chance, making a Coup de Grace critical strike very hard to land.
* Battle Trance negates Coup de Grace, preventing Troll Warlord from dying to her critical hits.

* 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 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.

* 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.

* 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.

* 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.

* Berserker's Rage will repeatedly trap Bloodseeker in a one-on-one fight.
* Whirling Axes (Melee) blinds Bloodseeker, causing him to miss 60% of the time, and therefore reduces his ability to gain the upper hand in teamfights.

* 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.

* The ensare from melee Berserker's Rage can prevent Primal Beast from dealing further Trample damage and can allow Troll Warlord to relentlessly build Fervor on him.
* Whirling Axes (Ranged) can slow down Primal Beast while trampling and allow Troll Warlord to better control him from range.
* Whirling Axes (Melee) can blind Primal Beast if he attempts to auto-attack Troll Warlord after a fully charged Uproar.
* Battle Trance will make Primal Beast a sitting duck should he be rooted and attacked to death. It might be wise to save Pulverize for after this spell is used so you have a defensive measure against Troll Warlord.

* Troll Warlord's ability to attack as a ranged hero allows him to destroy Juggernaut's Healing Ward from afar.
* Battle Trance, when activated during Omnislash, allows Troll Warlord to survive the full duration of Omnislash and retaliate once it is over.

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

* 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.

* 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.

* 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 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.

* 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.

* 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

* 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.

* 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.

* Whirling Axes (Melee) provides a 60% miss chance, which can make the attack speed bonus from Hunter in the Night largely ineffective.
* Berserker's Rage together with Battle Trance and Fervor stacks gives him a high chance of rooting Night Stalker, which allows Troll Warlord to man-fight Night Stalker in any stage of the game, regardless of whether or not it's night.
* Night Stalker is not a common Monkey King Bar carrier to counteract this problem.

* 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.

* Due to Fervor and Battle Trance, Troll Warlord has a significant attack speed, enabling him to crush Tombstone quickly.
* Undying usually stays at the front line with no disables, making him an easy target for Troll Warlord.

* 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 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.

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

* Viper can bully Alchemist out of mid lane quite easily, forcing him to either retreat into jungle, or stay harassed in lane, and get very few last hits. Vipers break also completely disables Greevil's greed which prevents Alchemist to earn his amazing amounts of money.

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

* 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.

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

* 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.

* 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.

* 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.

* 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.

* Heroes with a low attack speed or are fragile will find themselves unable to deal with Troll Warlord's high physical damage and attack speed, like Crystal Maiden or Sven.

* Terrorblade cannot go one on one against Troll Warlord as Troll Warlord will overwhelm him faster than the other way around thanks to Whirling Axes (Melee) that will cause his attacks to miss, and Fervor that can give Troll Warlord huge amounts of attack speed to outmatch Terrorblade, even during Metamorphosis.
* Troll Warlord's high attack speed from Fervor combined with Skull Basher and Abyssal Blade means that Terrorblade will have almost no chance to use Sunder to save himself.
* Even if Terroblade manages to use Sunder on Troll Warlord, Troll Warlord will simply be able to nullify it's effect with Battle Trance.
* Overall, any attempt for Terrorblade to engage and kill Troll Warlord will hurt him more than the other way around.
Additional:
* Terrorblade cannot go one on one against Troll Warlord as Troll Warlord will overwhelm him faster than the other way around thanks to Whirling Axes (Melee) that will cause his attacks to miss, and Fervor that can give Troll Warlord huge amounts of attack speed to outmatch Terrorblade, even during Metamorphosis.
* Troll Warlord's high attack speed from Fervor combined with Skull Basher and Abyssal Blade means that Terrorblade will have almost no chance to use Sunder to save himself.
* Even if Terroblade manages to use Sunder on Troll Warlord, Troll Warlord will simply be able to nullify it's effect with Battle Trance.

* Nethertoxin prevents Timbersaw from gaining stacks on Reactive Armor.

* Corrosive Skin makes Viper receive less damage from Invoker's spells
* Viper can harass Invoker with his Poison Attack in the early game.
* Viper Strike and Poison Attack can kill Invoker easily if Ghost Walk is on cooldown.

* 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.

* 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.

* 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.