Viper
* Even though Luna has a hard time laning against Viper due to 
Nethertoxin being able to disable 
Moon Glaives and 
Lunar Blessing, Luna can take out Viper once she builds either 
Black King Bar or 
Silver Edge which will allow her to attack Viper freely.
* 
Eclipse can often finish off Viper from early-to-mid stages of the game before he can retaliate as 
Corrosive Skin gives little magic resistance to him early on.
* 
Manta Style is an item that Luna commonly buys in most of the games, which lets her disjoint 
Viper Strike. Additionally, illusions from Manta Style can make Viper waste time attacking them.
Additional:
* Even though Luna has a hard time laning against Viper due to Nethertoxin being able to disable Moon Glaives and Lunar Blessing, Luna can take out Viper once she builds either Black King Bar or Silver Edge which will allow her to attack Viper freely.
* Eclipse can often finish off Viper from early-to-mid stages of the game before he can retaliate as Corrosive Skin gives little magic resistance to him early on.
* Manta Style is an item that Luna commonly buys in most of the games, which lets her disjoint Viper Strike. Additionally, illusions from Manta Style can make Viper waste time attacking them.
Centaur Warrunner
* Luna's Moon Glaives will not trigger 
Retaliate if they hit some other target first. Also Luna commonly buys items that provide lifesteal such as 
Satanic, which lets her heal from the damage of Retaliate, meaning that Retaliate has little effect against her.
* Eclipse can be used to counter-initiate against Centaur Warrunner after he jumps in with 
Blink Dagger, and initiates with 
Hoof Stomp. But remember that Centaur Warrunner can resolve this problem by buying 
Hood of Defiance and it's upgrade 
Pipe of Insight to diminish its damage. Or 
Blade Mail to reflect the damage of the Eclipse back at Luna.
* Luna also commonly buys Black King Bar, which will allow her to protect herself from both, Centaur Warrunner's abilities (except for the Retaliate), and damage reflect from Blade Mail.
Additional:
* Luna's Moon Glaives will not trigger Retaliate if they hit some other target first. Also Luna commonly buys items that provide lifesteal such as Satanic, which lets her heal from the damage of Retaliate, meaning that Retaliate has limited effect against her.
* Eclipse can be used to counter-initiate against Centaur Warrunner after he jumps in with Blink Dagger, and initiates with Hoof Stomp. But remember that Centaur Warrunner can resolve this problem by buying Hood of Defiance and it's upgrade Pipe of Insight to diminish its damage. Or Blade Mail to reflect the damage of the Eclipse back at Luna.
* Luna also commonly buys Black King Bar, which will allow her to protect herself from both, Centaur Warrunner's abilities (except for the Retaliate), and damage reflect from Blade Mail.
Viper
* Viper is an agility hero, and his item build mostly includes agility items, so Natural Order can be devastating, removing all armor and greatly decreasing the effectiveness of Corrosive Skin, weakening Viper's magic resistance. Additionally, Echo Stomp and Earth Splitter deal both magical and physical damage, and can help bringing Viper down fast.
* 
Aghanim's Scepter may be necessary to take Viper down due to Nethertoxin's break.
Viper
* Viper is kind of a mixed package. Tinker is very good against him. but stands a better chance against him than most heroes.
* Viper has a high innate magic resistance, but relies on his primary attacks to really deal damage. making Laser an effective way to save allies from him, and deal damage. Keep in mind that his Corrosive Skin will prevent Tinker from blinking.
* Viper's Viper Strike and 
Poison Attack will also have a hard time damaging allies through Tinker's constant casting of 
Defense Matrix.
* Viper has no solutions to cancel 
Rearm nor any of Tinker's escape attempts with 
Boots of Travel
* However, if Viper gets a jump on Tinker first. Tinker will unlikely survive versus Viper.
Viper
* Viper has no disable, which means he has no way of preventing Morphling from escaping from any of his abilities or keep him inside Nethertoxin.
* Viper is almost exclusively damage over time, which is weak against Morphling due to 
Attribute Shift (Strength Gain). Additionally, Morphling has no passive abilities, reducing Nethertoxin's effectiveness against him even further.
* Morphling can turn into Viper himself, allowing him to use any of Viper's abilities against him (excluding Viper Strike). This is particularly bad due to the fact that Viper is already a very slow hero, making Poison Attack and Corrosive Skin's slows especially difficult to deal with.
Viper
* 
Enfeeble weakens Viper's attack damage, any healing he receives and his cast range, which makes him unable to harass enemy heroes with Nethertoxin, Poison Attack and Viper Strike.
* 
Brain Sap allows Bane to heavily harass Viper, damaging him while healing Bane, which allows Bane to fight back against Viper's damage over time output, even through debuff immunity from Black King Bar.
* Viper's Corrosive Skin is useless against Bane as all of his damaging abilities deal Pure damage.
* Viper has no solutions to cancel 
Fiend's Grip and in addition, he hates buying disabling items like 
Eul's Scepter of Divinity.
Additional:
* Enfeeble weakens Viper's attack damage, any healing he receives and his cast range, which makes him unable to harass enemy heroes with Nethertoxin, Poison Attack and Viper Strike.
* Viper's Corrosive Skin is useless against Bane as all of his damaging abilities deal Pure damage.
* Viper has no solutions to cancel Fiend's Grip and in addition, he hates buying disabling items like Eul's Scepter of Divinity.
Centaur Warrunner
* 
Battery Assault easily interrupts Centaur Warrunner due to his poor cast animation.
* 
Power Cogs can negate Stampede.
Viper
* Clinkz does not have any passive abilities at all, making Nethertoxin nearly useless.
* Viper's Corrosive Skin provides no protection against Clinkz's physical damage output.
Viper
* Pugna's 
Decrepify allows him to save allies from being ganked by Viper, since Viper mostly relies on direct attacks in order to deal damage.
* 
Nether Ward can discourage Viper from spamming his abilities.
* Viper's damage over time is not enough to kill Pugna as he will have more than enough time to save himself (or his allies) with 
Life Drain and Viper has no solutions to cancel it.
* Pugna has no passive abilities, which renders Nethertoxin nearly useless.
Viper
* Viper's frailty and low mobility make him an enticing Duel target and Corrosive Skin doesn't protect him against Legion Commander physical attacks.
* Press the Attack can dispel Poison Attack.
* Viper slows can easily negate by Overwhelming Odds movement speed.
Centaur Warrunner
* Decay can be good against Centaur Warrunner, as reducing the health of Centaur can make 
Double Edge risky.
* His zombies do not proc Retaliate, as it only procs for regular attacks.
Viper
* Viper's lack of escape and durability means he can be ran over in a laning stage by 
Spawn Spiderlings.
* Broodmother can bring Viper down quickly with 
Insatiable Hunger activated.
Viper
* The Keeper of the Light easily farms on the line against the Viper, due to the fact that it has a long-range 
Illuminate, and the Viper, in turn, cannot use its advantage of dominance on the center line, due to the fact that it does not reach the Keeper of the Light
Additional:
* The Keeper of the Light easily farms on the line against the Viper, due to the fact that it has a long-range Illuminate, and the Viper, in turn, cannot use its advantage of dominance on the center line, due to the fact that it does not reach the Keeper of the Light
Viper
* Voodoo Restoration heals to counter damage over time of Viper abilities.
* Viper has no way to cancel Death Ward, even through 
Rod of Atos.
Viper
* 
Shukuchi ignores slows and allows Weaver to escape Viper's onslaught.
* 
Time Lapse dispels Poison Attack and Corrosive Skin and undoes poison damage.
* Weaver's high burst damage allows him to kill Viper before being killed.
Viper
* If Rubick can use 
Spell Steal to take Nethertoxin, he will be able to disable Corrosive Skin, reducing much of Viper's durability.
* He can also steal Viper Strike, which can be used to hinder a hero on your team (or multiple heroes, if Rubick has Aghanim's Scepter).
Viper
* 
Ball Lightning allows Storm Spirit to escape through Viper Strike, wasting Viper's mana.
* It's also very easy to wait out the duration of Nethertoxin's break.
Centaur Warrunner
* 
Winter Wyvern's 
Arctic Burn can also be a useful tool against Centaur, who generally has very high health. 
Winter's Curse on Centaur can cause Retaliate to damage allies who are forced to attack him.
Viper
* Viper cannot interrupt heroes with powerful channeling abilities: 
Bane, 
Enigma, 
Shadow Shaman, 
Warlock
Viper
* Heroes who rely on magical damage resistance may have a hard time laning against Dazzle as all of Dazzle's abilities deal physical damage instead of magical: 
Anti-Mage, 
Huskar, 
Viper.
Viper
* Heroes who do not have nor rely on passive abilities make Nethertoxin much less effective: 
Clinkz, 
Pugna, 
Nature's Prophet, 
Dark Seer, 
Lycan, 
Tusk
Viper
* Viper cannot interrupt heroes with powerful channeling abilities: Bane, Enigma, Shadow Shaman, Warlock
Viper
* Viper cannot interrupt heroes with powerful channeling abilities: Bane, Enigma, Shadow Shaman, Warlock
Viper
* Heroes who do not have nor rely on passive abilities make Nethertoxin much less effective: Clinkz, Pugna, Nature's Prophet, Dark Seer, Lycan, Tusk
Viper
* Heroes that can drain mana negatively affect Viper's ability to use Poison Attack, Nethertoxin and Viper Strike: 
Lion, Anti-Mage
Viper
* Heroes who do not have nor rely on passive abilities make Nethertoxin much less effective: Clinkz, Pugna, Nature's Prophet, Dark Seer, Lycan, Tusk
Viper
* Illusion or summon-based heroes can be a problem to Viper due to his lack of AoE damage: 
Naga Siren, 
Phantom Lancer, 
Beastmaster
Viper
* Viper's Nethertoxin cannot disable 
Reincarnation, which could put him in disadvantage against Wraith King if his whole team is with him.
* In addition, Viper doesn't like buying 
Diffusal Blade, which is the only item that can help him against Wraith King.
* Wraith King's high burst damage allows him to kill Viper before being killed.
Viper
* Melee heroes with low mobility can be kited and killed by Viper: 
Treant Protector, 
Kunkka, 
Alchemist, 
Troll Warlord, 
Wraith King, 
Tiny, 
Sven.
Centaur Warrunner
* 
X Marks the Spot negates Stampede.
Viper
* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.
Viper
* Almost all of Viper's damage revolves exclusively around single-target damage-over-time effects. Furthermore, without any hard disables, Terrorblade can almost always get a Sunder off.
* Viper has low mobility and Corrosive Skin doesn't protect against physical damage, which means that Terrorblade under Metamorphosis can quickly kill Viper.
Additional:
* Viper's damage over time and lack of disables makes him easy to 
Sunder.
* Viper's physical damage is mitigated by Terrorblade's high armor.
* Terrorblade under 
Metamorphosis can quickly kill Viper with heavy physical damage.
Centaur Warrunner
* As Terrorblade's damage output comes mainly from direct attacks, he will struggle greatly against heroes who have abilities that give evasion, trigger on attack or which can disarm an enemy hero: 
Centaur Warrunner, 
Hoodwink, Huskar, 
Invoker, 
Leshrac with 
Nihilism from Aghanim's Scepter, 
Lifestealer with Aghanim's Scepter upgraded 
Infest, 
Pangolier, 
Phantom Assassin, Pugna, 
Techies, 
Windranger etc.
Viper
* Viper Strike can be countered through Snowball, wasting Viper's mana through his ultimate. It's Viper Strike's break is also useless because he has no passive abilties at all. And to make things worse, Viper Strike cannot disable 
Walrus PUNCH! because it's an auto-cast ability
* As Tusk is a natural Silver Edge wielder, he can use it to disable Viper's magic resistance from Corrosive Skin, and make him vulnreable to his other allies.
Centaur Warrunner
* Durable heroes can stand against Tusk during 1v1: 
Axe, 
Dragon Knight, 
Night Stalker, Centaur Warrunner, Wraith King and more.
Viper
* Naga Siren can easily disjoint, and dispel Corrosive Skin with Mirror Image.
* Since Viper is mostly a single-target hero, he will not have almost any chance against Naga Siren because she is an illusion based hero.
* Viper has no burst damage, so Naga Siren will have plenty of time to use 
Aghanim's Shard upgraded 
Song of the Siren heal her allies before Viper can finish them off.
Centaur Warrunner
* Heroes who are reliant on illusions: 
Chaos Knight, Phantom Lancer, Naga Siren.
Additional:
* Centaur's Retaliate will harm all attacking enemies, which will allow Centaur Warrunner to see which is the real Naga Siren.
* A well timed Hoof Stomp followed by Double Edge will clear all Naga's illusions and prevent Naga Siren from escaping with Song of the Siren.
Viper
* 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.
Centaur Warrunner
* Whenever Doom casts his ultimate, Centaur Warrunner can cast Stampede and allow the 
Doomed hero to run away, wasting Doom's ultimate.
Additional:
* 
Stampede can be used to free an ally from the grasp of Doom. Without any means of effective lockdown, kills can be difficult to secure when against an enemy Centaur Warrunner. Also, Centaur's tendency to have lots of health and HP regen tend to help counter Doom.
Viper
* 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 Viper Strike, leaving Razor without his extra movement speed.
* 
Static Link's damage drain doesn't bother Viper a lot as most of his early to mid game damage is magical.
Centaur Warrunner
* Centaur can use Stampede to break Static Link. It also prevents Razor from chasing Centaur Warruner or his teammates with Eye of the Storm, and Plasma Field's slow will do nothing to slow them down.
Viper
* Viper Strike breaks Sniper's passives.
* Corrosive Skin allows Viper to deal more damage to Sniper than Sniper deals to him when laning, especially by briefly stepping into Shrapnel.
* Nethertoxin together with Poison Attack can slow Sniper and tears through his low health and mobility.
Centaur Warrunner
* 
Headshot and 
Shrapnel slow is ineffective against a team with haste (which Stampede gives).
* Commonly picked up mobility items and hasted movement during his Stampede (as well as his high health pool) make him extremely hard to kill from a distance, damaging 
Sniper with Retaliate and Blade Mail if he has one.
* A low health pool and no escape mechanism makes him an easy target for Centaur Warrunner's burst damage and initiation (even making his team possible initiators with Stampede).
Viper
* Corrosive Skin minimizes the damage from 
Impale and 
Mind Flare, and anything else Nyx Assassin tries to throw at Viper.
* Nyx Assassin cannot survive several poison damage-over-time output from Poison Attack, Nethertoxin, Corrosive Skin and Viper Strike, not even while he has 
Spiked Carapace active. And to make things worse, Nyx Assassin is not a common Silver Edge wielder to counter this problem at all.
Additional:
* Corrosive Skin minimizes the damage from Impale and Mind Flare, and anything else Nyx Assassin tries to throw at Viper.
* Nyx Assassin cannot survive several poison damage-over-time output from Poison Attack, Nethertoxin, Corrosive Skin and Viper Strike, not even while he has Spiked Carapace active. And to make things worse, Nyx Assassin is not a common Silver Edge wielder to counter this problem at all.
Centaur Warrunner
* Centaur's low Intelligence makes Mind Flare do low damage.
* With some creative skill builds, Centaur's Hoof Stomp stun duration should always last longer than Spiked Carapace stun, so escaping unscathed is hard for Nyx.
* With Blink Dagger and detection, Centaur can devastate Nyx in the open.
* However, bear in mind that Nyx can also easily initiate on Centaur Warrunner as well if he uses Spiked Carapace in anticipation, and with 
Vendetta. The damage from Retaliate will be reflected back to Centaur Warrunner, stunning him with no chance to react after he's revealed himself, and should guarantee a successful Impale.
Viper
* Viper Strike can disable 
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.
Centaur Warrunner
* Centaur Warrunner's passive Retaliate makes it so that the familiars cannot attack him without damaging themselves over time, in turn causing them to be destroyed.
Viper
* Heroes that can apply early pressure before Phantom Assassin has farm are massive threats: Axe, Viper, 
Meepo, 
Jakiro, Pugna, 
Slark, 
Venomancer etc.
Centaur Warrunner
* Hoof Stomp and Double Edge can often burst down Phantom Assassin from early to mid game.
* Retaliate makes it very unlikely for Phantom Assassin to win the lane against Warrunner. Double Edge can also be used to wear her down, as she has a much smaller health pool than that of Centaur Warrunner until purchasing a 
Ring of Health. 
Stifling Dagger will also trigger Retaliate and 
Blur cannot evade Retaliate.
* Centaur Warrunner's tankiness in combination with armour items that Axe often purchases like Blade Mail, 
Crimson Guard, 
Assault Cuirass and 
Shiva's Guard can make Phantom Assassin's attacks only tickle Centaur Warrunner.
* Centaur Warrunner just has to be careful about 
Fan of Knives from Aghanim's Shard and 
Coup De Grace, as Fan of Knives can disable Retaliate even if Centaur Warrunner is spell immune.
Additional:
* Hoof Stomp and Double Edge can often burst down Phantom Assassin from early to mid game.
* Retaliate makes it very unlikely for Phantom Assassin to win the lane against Warrunner. Double Edge can also be used to wear her down, as she has a much smaller health pool than that of Centaur Warrunner until purchasing a Ring of Health. Stifling Dagger will also trigger Retaliate and Blur cannot evade Retaliate.
* Centaur Warrunner's tankiness in combination with armour items that Centaur Warrunner often purchases like Blade Mail, Crimson Guard, Assault Cuirass and Shiva's Guard can make Phantom Assassin's attacks only tickle Centaur Warrunner.
* Centaur Warrunner just has to be careful about Fan of Knives from Aghanim's Shard and Coup De Grace, as Fan of Knives can disable Retaliate even if Centaur Warrunner is spell immune.
Viper
* 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:
* Viper STrike 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.
Centaur Warrunner
* Heroes that can keep Monkey King stunned for a long time can pose a threat: Axe, Centaur Warrunner.
Viper
* Poison Attack makes it hard for Void Spirit to lane against him.
* Corrosive Skin reduces the magical damage from Void Spirit's spells.
Centaur Warrunner
* Heroes who can match Void Spirit's mobility (like the aforementioned 
Ember Spirit or 
Queen of Pain) or tank his spells (Dragon Knight or Centaur Warrunner) are very problematic for him.
Viper
* Viper wins on the central line of Puck, because he has a huge damage from the Poison Attack ability, which Puck is not able to constantly avoid using 
Phase Shift, which will give Viper an advantage in the possible damage inflicted on each other
* Puck takes more damage than it does due to the passive Corrosive Skin ability of the Viper, which makes it unprofitable for the Puck to fight against the Viper at an early stage of the game, when the Puck has a very small pool of health.
Additional:
* Viper wins on the central line of Puck, because he has a huge damage from the Poison Attack ability, which Puck is not able to constantly avoid using Phase Shift, which will give Viper an advantage in the possible damage inflicted on each other
* Puck takes more damage than it does due to the passive Corrosive Skin ability of the Viper, which makes it unprofitable for the Puck to fight against the Viper at an early stage of the game, when the Puck has a very small pool of health
Centaur Warrunner
* Axe, 
Bristleback, Centaur Warrunner, 
Spirit Breaker, 
Pudge, Huskar, Wraith King, 
Doom: 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.
Viper
* Heroes with break can disable Untouchable for a while: Doom and 
Shadow Demon (via Aghanim's Scepter), Viper, Shadow Shaman with Hex Breaks talent.
Centaur Warrunner
* Heroes with haste can negate Enchant's slow: 
Weaver, Dark Seer, Lycan, Centaur Warrunner.
Viper
* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.
Centaur Warrunner
* Heroes who thrive on teamfights can be a problem, such as Venomancer, 
Necrophos, Centaur Warrunner...
Viper
* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.
Centaur Warrunner
* Troll Warlord's high speed attack makes Retaliate deal a lot of damage to him.
Viper
* Viper Strike prevents buildup of Fiery Soul stacks.
* Corrosive Skin provides magic resistance against Lina's spells. However, Lina can counter this with Silver Edge, a common item on Lina.
* Poison Attack and Viper Strike can burn away Lina's small health pool.
Viper
* 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.
Centaur Warrunner
* Pangolier will proc Retaliate several times if he attempts to use 
Swashbuckle on Centaur Warrunner.
* Centaur can cast Stampede to allow all of his allies to easily avoid 
Rolling Thunder.
* Centaur's tankiness makes it hard for Pangolier to burst him down in the late game.
Additional:
* When Swashbuckle hits Centaur Warrunner, Retaliate will deal significant damage, as it procs off every strike made.
* Stampede helps allies avoid or disengage from Pangolier during Rolling Thunder, as well as neutralizing the slow debuff from Lucky Shot.
Viper
* Viper Strike prevents Timbersaw from gaining stacks on Reactive Armor.
Viper
* 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.
Viper
* 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:
* Viper Strike can disable 
Bulwark entirely, making Mars far less tanky. Using Nethertoxin inside 
Arena of Blood may discourage enemies from following up with Mars's initiation.
* Rod of Atos is currently common on Viper and keeps Mars in position long enough to be killed.
* However, Viper is not very tanky earlier in the game, so positioning against Mars is important for Viper since a well-timed 
Spear of Mars can be the end of Viper.
Viper
* 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.
Viper
* Nethertoxin 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 breaks and Poison Attack. Poison Attack also serves as a great way to harass Shadow Fiend.
Viper
* 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 and Nethertoxin.
* Corrosive Skin reduces damage from Dragon Fire and inflicts damage to him.
* Viper Strike 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.
* Viper Strike can disable 
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.
Viper
* 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.
Centaur Warrunner
* Stampede can allow Soulbinded heroes to just ran away.
Centaur Warrunner
* A good Centaur can catch Queen of Pain with a Blink Dagger and Hoof Stomp.
* Retaliate with Blade Mail reflects all of Queen of Pain's damage, especially Sonic Wave.
* Stampede grants a movement speed bonus, which can prevent Queen of Pain from initiating.
* Double Edge can shred her low health pool if she's not careful.
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.
Viper
* Viper Strike breaks Multicast.
* Corrosive Skin minimizes the damage from Ignite and Fireblast.
Viper
* Heroes that can drain mana negatively affect Viper's ability to use Poison Attack, Nethertoxin and Viper Strike: Lion, Anti-Mage
Viper
* 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.
Centaur Warrunner
* Anti-Mage's 
Mana Void won't do a lot of damage because Centaur has a low mana pool. 
Mana Break is also relatively ineffective against him.
Viper
* 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:
* Viper Strike can disable 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
* Nethertoxin disables Dawnbreaker's 
Luminosity. 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.
Viper
* Nethertoxin disables Bristleback's passive.
* Viper Strike and Poison Attack slow down Bristleback's movement speed, making him unable to get out from Nethertoxin.
Additional:
* Viper Strike can disable 
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.
Viper
* 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.
Viper
* Poison Attack and Viper Strike slows Axe significantly, and puts his Blink Dagger on cooldown, preventing him from initiating. Viper Strike can also break from Counter Helix.
Additional:
* Viper Strike 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
* Because Poison Attack has almost no cooldown, Aphotic Shield is ineffective as a hard dispel.
* Viper Strike can prevent 
Borrowed Time from activating passively and block 
Curse of Avernus.
Additional:
* Because Poison Attack has almost no cooldown, 
Aphotic Shield is ineffective as a hard dispel.
* Viper Strike can prevent Borrowed Time from activating passively and block Curse of Avernus.
Viper
* Viper Strike is a strong and breaks Fury Swipes, undispellable slow, making it much easier to kite Ursa for everyone.
Viper
* 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.
Viper
* 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.
* Viper Strike can disable 
Aftershock, which removes the stun and bonus damage from Enchant Totem and 
Echo Slam.
Viper
* Viper STrike 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 like Viper.
* Tidehunter relies on the threat of 
Ravage, which has an obscenely long cooldown. Viper can exploit the downtime with his short cooldowns.
Viper
* 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:
* Viper Strike can disable 
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.
Viper
* 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:
* Viper Strike can disable 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.
Viper
* 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
* Viper Strike 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.
Viper
* 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.
Viper
* 
Windrun evades Poison Attack and counteracts the slow.
* Viper's low mobility makes him an easy 
Shackleshot target.
* 
Focus Fire grants Windranger significant physical damage output to quickly wear Viper down.
* 
Powershot is a strong harassment and zoning tool against Viper in lane.
Viper
* Since Windranger is bad against magical damage, heroes with continuous magical damage or magical nukes can blast her: 
Zeus, 
Tinker, Leshrac, Viper, 
Skywrath Mage, Lion, 
Lina, Venomancer.
Centaur Warrunner
* Focus Fire grants Windranger a massive attack speed bonus, while her attack damage is generally quite low. This, combined with Windranger's low health pool and armor, makes Retaliate do absolutely massive damage over a short time, making Centaur a hero she can never expect to kill or harass.
* Windrun grants evasion, but Centaur Warrunner does not rely on successful attacks in order to do damage. Hoof Stomp, Double Edge, and Stampede all do large amounts of magical damage and can completely demolish Windranger in a moment.
Additional:
* Stampede can help his teammates escape from Windrun and Focus Fire.
* Retaliate will shred through Windranger's health if she chooses to attack him during Focus Fire.
Viper
* 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's 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.
Viper
* Melee heroes with low mobility can be kited and killed by Viper: Treant Protector, Kunkka, Alchemist, Troll Warlord, Wraith King, Tiny, Sven.
Viper
* 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.
Centaur Warrunner
* Heroes that can stop Faceless Void from leaping around the fight and controlling its outcome are very strong against him. Heroes such as: Axe, Centaur Warrunner, Doom...
Viper
* Heroes with Break abilities will prevent Slark from regenerating and gaining Essence Shift stacks: Viper, Shadow Demon, etc.
Additional:
* Viper Strike can disable 
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).
Viper
* 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.
Centaur Warrunner
* Night Stalker is all about right-clicks. His nuke, 
Void is also not that threatning once you have Hood of Defiance, your core item.
Viper
* Heroes who can harass Omniknight out of lane will keep him weak in the mid game: Viper, Venomancer, Clinkz.
Viper
* Heroes that can slow Charge of Darkness by a huge amount: Venomancer, Viper, Dazzle, 
Arc Warden, Lion, Huskar, Shadow Shaman, 
Visage, 
Undying, Jakiro.
Centaur Warrunner
* Heroes who have low or high armor but very high health will be difficult for drow to burst down quickly: 
Primal Beast, Axe, Centaur Warrunner.
Centaur Warrunner
* Heroes that are hard to gank: Axe, 
Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, 
Medusa, 
Mars.
Viper
* 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.
Viper
* Ranged heroes will have a hard time hitting enemies inside Magnetic Field: 
Silencer, Viper.
Centaur Warrunner
* Arc Warden cannot take Centaur Warrunner very easily, and his nukes are not strong enough to deal with Centaur Warrunner.
* Centaur Warrunner deals huge AoE damage and applies an AoE disable through Hoof Stomp, affecting the double as well the main Arc Warden.
* 
Magnetic Field is not very effective against melee heroes. And to make things worse, Magnetic Field also increases Arc Warden and his allies's attack speed, meaning Retaliate will deal more damage.
* Stampede catches Arc Warden easily due to his lack of escape mechanisms. However, Arc Warden can counter this problem with 
Gleipnir, which is a common item on Arc Warden.
Viper
* As Viper focuses on single-target damage, he has trouble fighting off Phantasm illusions.
* Reality Rift counteracts Viper's slows and reduces his already low durability against physical damage.
Additional:
* Viper has no response to the standard initiation combo of 
Reality Rift into 
Chaos Bolt.
* 
Phantasm and 
Chaos Strike can eliminate Viper almost instantly with it's damage output.
* Besides Nethertoxin, Viper has no other ways of dealing with Phantasm.
Viper
* Heroes with Attack speed decreasing skills: Jakiro, Viper 
Lich
Centaur Warrunner
* Heroes who are reliant on illusions: Chaos Knight, Phantom Lancer, Naga Siren.
Viper
* Although Viper Strike cannot be dispelled by Doppelganger, Viper's lack of mobility and AoE damage makes him an easy target for Phantom Lancer.
* Viper's various slows do not work against 
Phantom Rush.
* Although Phantom Lancer should be wary due to Nethertoxin applying Break.
Additional:
* Phantom Lancer can overwhelm Viper with spawned illusions from 
Spirit Lance and 
Doppelganger. In addition, Diffusal Blade, a core item on Phantom Lancer, burns Viper's limited mana pool, reducing his potential poison damage.
* Viper's various slows do not work against Phantom Rush. Additionally, it is almost impossible to keep Lancer inside Nethertoxin's radius in order to disable the passive.
Centaur Warrunner
* His illusions will kill themselves in a few hits because of Retaliate. The nukes from Hoof Stomp and Double-Edge should be enough to clear them for a large portion of the game
* Centaur Warrunner's small mana pool makes Diffusal Blade's damage much lower once Centaur doesn't have any more mana left to burn. Keep in mind that Double Edge does not cost mana.
* Be wary when chasing down Phantom Lancer. Hoof Stomp's terrible cast time makes it quite easy to dodge with Doppelganger.
Additional:
* Hoof Stomp and Double Edge makes short work of Phantom Lancer's illusions.
* Retaliate together with Blade Mail reflects Phanton Lancer's damage and quickly destroys his illusions.
Centaur Warrunner
* With high health and rarely buying 
Linken's Sphere or Black King Bar, Centaur Warrunner is a good target for 
Reaper's Scythe. However, Centaur Warrunner can resolve this problem by buying Hood of Defiance and it's upgrade Pipe of Insight to diminish its damage.
* 
Heartstopper Aura will do well against high health heroes such as Centaur Warrunner.
Viper
* 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 Necrophos spells that deal magical damage, which is his only source of damage.
Additional:
* Viper Strike 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.
Centaur Warrunner
* Centaur has nothing to deal with 
Refraction that will negate all of his burst damage.
* 
Psionic Traps provide good vision, making for him harder to initiate.
Viper
* 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 usually buys health and armor items for damage. Outside of Black King Bar, Viper will almost always be able to kill her when Refraction is down.
Viper
* 
Ice Wall and 
Ghost Walk can be used to kite and escape from Viper.
* 
Chaos Meteor and 
Sun Strike deal heavy damage and can quickly bring Viper down.
* 
Cold Snap, 
Tornado, and 
Deafening Blast are powerful disables that reduce Viper's effectiveness.
* 
E.M.P. burns Viper's limited mana pool, reducing his potential poison damage.
* 
Forge Spirits can melt Viper's armor and reduce his durability.
Viper
* 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.
Centaur Warrunner
* 
Kinetic Field and 
Glimpse can completely negate Stampede.
Viper
* Corrosive Skin minimizes the damage Viper takes from all of Disruptor's skills.
Viper
*
Rage ignores all of Viper's magical damage, although 
Viper Strike can pierce spell immunity and slows him down.
Feast and 
Open Wounds from 
Aghanim's Shard can be combined to heal through Viper's physical damage.
Aghanim's Scepter upgraded 
Infest can be used to disarm Viper, preventing him from using 
Poison Attack on Lifestealer's allies.
*
*
Centaur Warrunner
*
Feast is an effective tool against Centaur Warrunner, who generally has high health and low armor, and compensates the reflected damage of Retaliate.
Rage can protect Lifestealer from Hoof Stomp, Double Edge, and Stampede.
Hoof Stomp's slow wind up can also be anticipated and negated with Rage.
Retaliate's damage return simply with Feast. Centaur's high strength gain and therefore big health pool makes him an ideal target to Feast on, especially in the late-game.
* If activated,
Additional:
* Centaur Warrunner's active abilities cannot pierce magic immunity.
* Lifestealer can offset