* 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.

* His Rot can force Templar Assassin out of her Meld and destroy all of her Refraction charges quickly, and her small health pool and meager defense make her very vulnerable to his Meat Hook without Refraction.

* Pudge's Dismember stops Spectre from escaping with Haunt.
* He can easily tank the damage reflected by Dispersion due to his high strength and the healing from Dismember.
* Should Spectre try to get away through the trees or over a cliff with Spectral Dagger, Pudge can hook her back.
* Spectre takes a long time to become powerful, and Pudge can ruin her early game with ganks.

* 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.
Additional:
* 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.

* Sniper has a low health pool and strength gain, making him vulnerable to Pudge's magical and pure damage.
* Sniper usually likes to deal damage away from the fight, and Meat Hook is capable of bringing him to the front lines.
* Assassinate won't do much damage against Pudge because of his high strength gain and the strength bonuses from Flesh Heap.
* Shrapnel will be mostly blocked by Flesh Heap's active.
Additional:
* Pudge's Meat Hook allows him to bring Sniper in the middle of any fight, and the pure damage does well against his high armor and low health.
* Dismember can lock Sniper down, which makes him highly vulnerable and gives enough time for Pudge to kill him alone.

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

* Zeus likes to stay far back in fights, dealing his damage uninterrupted, but once he gets hooked into the fight, he usually dies very quickly.
* Pudge's high strength from Flesh Heap makes it very hard for Zeus to burst him down.
* Zeus' low health pool makes him very vulnerable to the damage from Meat Hook, Rot and Dismember.
Additional:
* Meat Hook's high range allows Pudge's team to drag Zeus in the middle of the fight and abuse his frailty.
* Flesh Heap's health and magic resistance bonus makes Pudge exceptionally resistant to Zeus' nukes. In later stages of the game, Zeus is usually unable to seriously damage Pudge at all. Even Static Field, which deals damage based on a percentage of the enemy's health, won't be doing much.
* Even if Zeus buys a Black King Bar, Meat Hook and Dismember still disable him for a long time, usually causing Zeus' quick death.
* Zeus is vulnerable to early ganks, which Pudge excels at.

* 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.
Additional:
* 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.

* 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.

* Heroes with channeling spells because Shadow Fiend has nothing to cancel channeling outside of Requiem of Souls: Bane, Enigma, Pudge, Shadow Shaman, Dawnbreaker, Warlock, Crystal Maiden.

* Because only one clone needs to be killed in order to kill Meepo, heroes that excel at singling out enemies can also be a detriment to him, such as Batrider, Beastmaster, Pudge and Clockwerk.

* 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.

* Heroes with large health pools (Pudge) or good innate magic resistance (Anti-Mage) can be very problematic for Crystal Maiden, since even if they are under the effect of her ultimate for the entire duration, the damage output is simply not enough to kill or force them to retreat.

Additional:
* Meat Hook can cancel Freezing Field, even if Crystal Maiden has Glimmer Cape.
* She is also slow and fragile, making her a good target for ganking.

* 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.

* 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.
Additional:
* 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.

* Meat Hook can be used immediately after Mortimer Kisses since Snapfire is forced to stay in place.

* 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.

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

* 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.
Additional:
* 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.

* Rot and Meat Hook hits Dark Willow even when she uses Shadow Realm.
* Flesh Heap reduces Dark Willow's magic burst damage.

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

* 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.

* 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.

* 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.

* 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.

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

* 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.

* Meat Hook can hit and displace Juggernaut during his Blade Fury.
* Dismember pierces Juggernaut's spell immunity from Blade Fury.

* 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.

* 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.
Additional:
* 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.

* Meat Hook brings Drow Ranger to Pudge, disabling Marksmanship and dealing a huge amount of damage when combined with Rot and Dismember.
* Rot keeps Pudge close to Drow Ranger, continuously disabling Marksmanship.
Additional:
* Meat Hook can pull Drow Ranger to Pudge, disabling her Marksmanship.
* Following up with Dismember will prevent Drow Ranger from using Gust or Shadow Blade.

* Meat Hook can be used to pull Tinker to Pudge while he is hiding in the trees, and a follow up with Dismember and Rot can lead to a valuable kill, as Tinker doesn't buy many survivability items.
* Flesh Heap makes it hard for Tinker to deal serious damage.
Additional:
* He can Meat Hook a Tinker hiding in the trees and follow it up with Dismember and Rot for an easy solo kill, as Tinker doesn't tend to buy survivability items.
* His innate magic resistance and huge health pool from Flesh Heap makes it hard for Tinker to deal serious damage to Pudge.

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

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

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

* 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.

* Heroes with abilities that can pull Lina out of position can easily bring her to their team mates, like Batrider with Flaming Lasso, Pudge with Meat Hook and Vengeful Spirit with Nether Swap.

* 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 other kind of disables that pierce spell immunity can hold Pangolier in place during Rolling Thunder: Axe, Beastmaster, Enigma, Magnus, Pudge, Batrider, Bane, Winter Wyvern

* Abilities that deal low damage with high amounts of instances are irrelevant against Pudge during Flesh Heap's active: Gyrocopter's Rocket Barrage and Dark Seer's Ion Shell are just a couple examples.

* Heroes who recklessly jump on Pudge with their gap-closing abilities will be easy targets for Pudge's Meat Hook and Dismember Combo: Phantom Assassin, Faceless Void, Queen of Pain etc.

Additional:
* Meat Hook can pull an ally out of Chronosphere.
* Rot will keep damaging Void if he toggled it before Chronosphere, but you can lower your hp for Faceless Void.
* Flesh Heap will help Pudge survive through the Chronosphere with enough stacks, and follow with Dismember.

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

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

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

* 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.

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

* If Phantom Assassin jumps on Pudge first with Phantom Strike, she will be a very easy target for Pudge's Meat Hook and Dismember combo.
* Even though it can deal damage based on Pudge's max health, Fan of Knives from Aghanim's Shard cannot disable Pudge's Flesh Heap as Flesh Heap is one of the few passive abilities that cannot be disabled by break.
* Both Meat Hook and Dismember ignore spell immunity which allows Pudge to disable Phantom Assassin even while she has Black King Bar active.
* Pudge occassionally buys armor items like Blade Mail, which in combination with many stacks from Flesh Heap can make Phantom Assassin have little effect against Pudge.

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

* 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.

* 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.

* 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 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 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.
Additional:
* 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.

* Nethertoxin prevents Timbersaw from gaining stacks on Reactive Armor.

* 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.
Additional:
* 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.

* Heroes who recklessly jump on Pudge with their gap-closing abilities will be easy targets for Pudge's Meat Hook and Dismember Combo: Phantom Assassin, Faceless Void, Queen of Pain etc.

* 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.

* 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.

* 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.

* Even with Black King Bar, Pudge's Meat Hook can still catch Bane while channeling Fiend's Grip, as a result, breaking the channel, Meat Hook can also be used to save targets affected by Bane's abilities.
* Dismember can disable Bane while channeling Fiend's Grip if Pudge is not targeted.
* Pudge's high health and health regeneration allows him to survive through most of Bane's abilities.

* Abilities that deal low damage with high amounts of instances are irrelevant against Pudge during Flesh Heap's active: Gyrocopter's Rocket Barrage and Dark Seer's Ion Shell are just a couple examples.

* Flesh Heap's magic resistance allows him to survive Eclipse, and Meat Hook and Dismember can disable Luna through her Black King Bar.
* However, Lucent Beam can still cancel Dismember from a safe distance, even if its damage is going to be reduced.

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

* 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.

* Heroes that have a channeled ability that can be interrupted by Meat Hook: Shadow Shaman, Witch Doctor, Enigma, Bane.

* 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.

* 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

* 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).

* 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 build a Black King Bar (or have any sources of spell immunity) to channel abilities/items can still get interrupted by Dismember: Enigma, Juggernaut, Phantom Assassin, Pugna, Elder Titan.

Additional:
* Even with Black King Bar, Pudge's Meat Hook and Dismember can still disable Engima while he is channeling Black Hole.
* Pudge's Aghanim's Shard upgraded Dismember and Meat Hook are great ways to save allies from Black Hole.
* Enigma is prone to ganks in the jungle or in the off-lane without proper vision. Pudge can take advantage of Enigma's lack of mobility, and gank him often.

* 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.

* 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.

* 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.