* Rage protects Lifestealer from all of Lina's abilities (except an upgraded Laguna Blade).
* Open Wounds is great to keep Lina in place because she has no abilities to help her escape.

* 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.

* 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.

* Feast deals damage and heals Lifestealer based on the target's maximum HP, which is greatly effective against naturally high HP heroes such as Doom.
* Rage allows Lifestealer to become spell immune to negate the magical damage of Infernal Blade and Scorched Earth.
* Doom has no effective means of escape from Open Wounds. This is particularly devastating in lane, where Doom may have to play a much more passive, conservative play style as a result.

* 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.

* Rage protects Lifestealer from all of Techies' magic damage and disables and dispels Reactive Tazer's debuff .
* Usually teams will have a hard time pushing high-ground against Techies, but Lifestealer can just pop Rage and walk uphill without fear of Techies.
Additional:
* Lifestealer's Rage lets him clear Proximity Mines without taking damage, and allows him to hit heroes whom Techies has used Reactive Tazer on.

* 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.

* Rage, acting as a pseudo-Black King Bar, completely negates Mars' initiation if used in time.
* Feast does damage and heals based on max health, perfect against high-health strength heroes like Mars.
* Infest allows Lifestealer to potentially save allies from Mars' initiation with a quick burst of extra health.

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

* Lifestealer's Rage makes him immune to all of Ogre's magical debuffs and also dispels them.
* Ogre's as hero with great durability and high health is great target for Lifestealer in any stage of the game, thanks to Feast.
Additional:
* Ogre Magi has nothing against Rage and his high health pool amplifies Feast.

* Feast makes it impossible to put Lifestealer's health for a Culling Blade and also deals high damage to Axe due to his naturally high health.
* However, Lifestealer's Rage can be pierced by Berserker's Call, Counter Helix and Culling Blade.

* 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.

* Feast will deal a enormous amount of damage because of Tiny's huge health pool.
* Rage protects Lifestealer from Tiny's magical burst damage.

* 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.

* Feast deals damage and heals lifestealer based on the target max health. Because Spectre often emphasises on building stat items to increase her HP pool, lifestealer can deal a lot of damage to her and heal himself at the same time.
* Ghoul Frenzy slows target, which is bad for Spectre if she does not have Spectral Dagger ready.
* Spectre cannot response to infest if lifestealer choose to stay inside his high mobility allies to approach the backline. Rage's bonus movement speed and spell immunity make it even more frustrating.

* 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.

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

* Lifestealer can close the distance to Sniper by using Infest on a fast or durable creep to tank Sniper's damage.
* Open Wounds and Ghoul Frenzy will reduce Sniper's mobility heavily, and Rage's movement speed bonus helps in closing the gap to Sniper. It also protects him from Assassinate and Shrapnel.
* Infest can dodge an incoming Assassinate.

* Rage is very useful against Zeus, as it negates magic damage and provides spell immunity. In addition, the increased attack speed can tear Zeus apart in combination with Open Wounds.
* Lifestealer can avoid Thundergod's Wrath with Infest.

* 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.

* Rage can be used to escape from a Glimpse and to move out of Kinetic Field.
* Infest allows Lifestealer to dodge Glimpse.

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

* Being a strength hero with a high strength gain means Feast can give her a hard time,especially later in the game.
* However,Starbreaker's physical damage can control him in the laning phase.

* 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.

* 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.

* Rage prevents Earthshaker from damaging and stunning Lifestealer.
* Feast is very effective against Earthshaker, because of him being a strength hero, allowing Lifestealer to heavily harass and kill him.
* Open Wounds prevents Earthshaker from escaping after he initiated.
* Infest gives Lifestealer an easy way to escape should he get caught out by Earthshaker.

* 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.

* Rage renders Lifestealer immune to the damage from Burning Spears.
* Feast makes Lifestealer one of few heroes that can outlast Huskar in a one-on-one fight.

* Rage completely negates all of Nyx Assassin's abilities except Vendetta, while Open Wounds allow him to quickly close the gap.
* Infest combined with an ancient creep makes Nyx Assassin an easy target with Dust of Appearance or a Gem of True Sight.

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

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

* Feast is good against high health strength heroes such as Alchemist.
* Rage allows Lifestealer to not be targetable by Unstable Concoction, possibly making Alchemist stun himself.

* Rage negates Kunkka's X Marks the Spot.
* As a strength hero with high strength gain and very little armor, as well as low agility gain, Kunkka is vulnerable to Lifestealer's Feast and Open Wounds.

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

* Heroes with burst damage of their own won't be afraid to go toe to toe with Void Spirit, like Ursa, Lifestealer, or Axe.

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

* Heroes with spell immunity-granting spells will render Phoenix useless against them, as Phoenix has almost no spell immunity-piercing ability, other than the stun at the end of Supernova: Lifestealer, Juggernaut.

* 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.

* Lifestealer with Rage and Infest
* Heroes that can remove the Track debuff with their skills:
* Abaddon with Aphotic Shield and Borrowed Time
* Huskar with Life Break
* Juggernaut with Blade Fury
* Legion Commander with Press the Attack
* Lifestealer with Rage and Infest
* Naga Siren with Mirror Image
* Omniknight with Heavenly Grace
* Oracle with Fortune's End and False Promise
* Phantom Lancer with Doppelganger
* Slark with Dark Pact
* Ursa with Enrage
* Weaver with Time Lapse
* Tidehunter with Kraken Shell when damage received reaches the threshold.

* 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 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.

* Rage can protect Lifestealer from most of the Silencer's abilities with the exception of Global Silence.
* If Lifestealer can Infest himself on any unit, he can literally avoid being affected by Global Silence.
* Against a carry Silencer, Aghanim's Scepter upgraded Infest can disarm him and allow Lifestealer to attack Silencer from within, even if Silencer is spell immune.
* Open Wounds from Aghanim's Shard can severely slow down Silencer, and allow Lifestealer and his team to heal themselves by attacking Silencer.
Additional:
* Rage can protect Lifestealer from most of the Silencer's abilities with the exception of Global Silence.
* If Lifestealer can Infest himself on any unit, he can literally avoid being affected by Global Silence.
* Against a carry Silencer, Aghanim's Scepter upgraded Infest can disarm him and allow Lifestealer to attack Silencer from within, even if Silencer is spell immune.
* Open Wounds from Aghanim's Shard can severely slow down Silencer, and allow Lifestealer and his team to heal themselves by attacking Silencer.

* Lifestealer deserves a special mention because in a fight to the death with equal farm, his lifesteal will do no where near as much sustain as Gods Strength's damage output. However, Rage means he can always disengage at will if he's quick on the trigger. This is one of those matchups that can really go either way.

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

* 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 that can instantly kill creeps greatly reduce the effectiveness of Chen's converted army: Lifestealer, Doom, Mirana, Clinkz.

* Juggernaut and Lifestealer have abilities (Blade Fury and Rage respectively) that prevent Crystal Maiden from using her spells on them in the early game, before Black King Bar and other magical reduction is even an issue.

* 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.

* Nethertoxin prevents Timbersaw from gaining stacks on Reactive Armor.

* 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.

* Rage protects Lifestealer from all of Dark Willow's abilities.
Additional:
* Rage protects and dispels all of Dark Willow's 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.

* Rage protects Lifestealer nearly from all of Invoker's spells.
Additional:
* Rage grants immunity from Invoker's spells and can dispel most of the disables such as the armor loss from Forge Spirit and the constant stuns of Cold Snap.

* Rage ignores all of Gyrocopter's magical attacks.
* Feast helps Lifestealer out-damage Gyrocopter at close range.

* With Feast and Rage, Lifestealer is nearly impossible for Clockwerk to bring down, and is the last hero Clockwerk wants to be trapped with in Power Cogs.

* The lifesteal of Feast scales accordingly to the max health of its target, which is effective against Pudge due to his high health and further health granted by stacks of Flesh Heap.
* Lifestealer can activate Rage to be spell immune, making Rot deal no damage.
* Pudge's plentiful health makes him an ideal target for Lifestealer's Aghanim's Shard ability, Open Wounds.

* Rage grants Lifestealer immunity to all of Jakiro's spells. Note: magic resistance will not dispel the attack speed slow effects from Dual Breath and Liquid Fire.

* 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.

* Lifestealer's Rage renders him immune to all of Marci's disables and magic damage for a good duration.
* His passive Feast deals bonus damage based on the enemy's max health and heals for the same amount. As a tanky Strength hero, Marci's own strength will be her undoing as well.

* 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

* Feast is an effective tool against Centaur Warrunner, who generally has high health and low armor, and compensates the reflected damage of Retaliate.
* If activated, Rage can protect Lifestealer from Hoof Stomp, Double Edge, and Stampede.

* 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.

* Lifestealer is not affected by Earthbind or Poof during Rage, making him a difficult target to work around.

* Leshrac's high magic damage is ignored by Rage.
* Lifestealer can get in Leshrac's face with Rage and mitigate any other damage taken by Leshrac with Open Wounds.

* 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.

* Rage will dispel Laser's blind and turns him spell immune for the duration so Tinker cannot damage him.
* Feast will quickly bring down Tinker due to being so fragile.
Additional:
* Lifestealer's Rage makes him immune to all of Tinker's damage and debuffs.
* Lifestealer can infest any mobile hero (teams usually pick one against Tinker), which ensures that Tinker will die if he is caught.

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

* Heroes with magic immune abilities can negate most of Visage's attacks like Pangolier and Lifestealer.

* Special mention to Lifestealer as he has magic immunity in Rage which protects agaisnt Primal Beast. However, if he doesn't use it the long chain stun potential can be deadly, denying him to use Feast for a lengthy time.

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

* Heroes with built-in spell immunity can become immune to all of Outworld Destroyer's spells: Lifestealer's Rage and Juggernaut's Blade Fury.

* In general, heroes with spell immunity abilities won't be caught inside by Pit of Malice: Juggernaut, Lifestealer.

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

* With Aghanim's Scepter upgraded Infest, Lifestealer can use it on enemy heroes to attack them and disarm them from inside, even if they are spell immune, which can give him the edge over the heroes he's weak against like Ursa, Phantom Assassin, Terrorblade or Troll Warlord.

* 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.

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

* 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.

* 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.

* 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.

* Rage provides spell immunity to Lifestealer and thus nullifies all of Lion's abilities.
* Open Wounds allows Lifestealer to easily catch Lion out and prevent him from escaping.

* 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.

* 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.

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

* With Aghanim's Scepter upgraded Infest, Lifestealer can use it on enemy heroes to attack them and disarm them from inside, even if they are spell immune, which can give him the edge over the heroes he's weak against like Ursa, Phantom Assassin, Terrorblade or Troll Warlord.

* With Aghanim's Scepter upgraded Infest, Lifestealer can use it on enemy heroes to attack them and disarm them from inside, even if they are spell immune, which can give him the edge over the heroes he's weak against like Ursa, Phantom Assassin, Terrorblade or Troll Warlord.

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

* Heroes who have most or all their abilities (damage or disable) unable to pierce spell immunity: Keeper of the Light, Lina, Lion, Zeus.

Additional:
* Rage allows him to be immune to all of Ezalor's abilities. Also, the increased movement speed combined with the slow from Ghoul Frenzy and the squishy nature of Ezalor allows Lifestealer to take him down very quickly.

* 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.

* Heroes with spell immunity or pseudo-blinks which provide invulnerability: Lifestealer, Juggernaut, Omniknight, Huskar , and Tusk have spells which allow them to easily escape Dream Coil.

* Lifestealer's Rage negates Sand King's spells which do magical 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.

* 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).

* Slark, Lifestealer, Morphling and other heroes with good escape mechanisms are a nuisance to deal with in the early phase of the game.

* 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.