* Rubick can turn around entire teamfights if he manages to steal Reverse Polarity.
* Shockwave allows Rubick to farm pretty fast together with Fade Bolt, and also deals decent AoE damage in teamfights.
* If Rubick steals Skewer, he can use Telekinesis to displace enemies and Skewer them away.
Additional:
* All of Magnus's spells are perfect for Rubick to steal, especially Reverse Polarity for a counter-initiation.
* Telekinesis is one of the best instant-disables in the game, completely ruining Magnus's initiation.

* 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.

* All of Vengeful Spirit abilities are very good for Rubick to Spell Steal:
* Magic Missile provides an additional nuke/disable to pair with Fade Bolt and Telekinesis, respectively.
* Wave of Terror serves as a good scouting/armor reduction skill that Rubick and his team can benefit from.
* Nether Swap complements Rubick's mobility and pairs well with other mobility items he usually builds. He can also use it to save an ally from danger.

* 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 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.

* Rubick will find all Lina's abilities useful:
* Dragon Slave provides a good way to clear creep waves and allows Rubick to deal tons of magical damage in teamfights.
* Light Strike Array gives Rubick a solid area stun, which is easy to set up right after Telekinesis.
* Laguna Blade gives Rubick a massive damage boost and great solo kill potential.

* 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.

* 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. Additionally the level 25 talent will silence Earthshaker, making him vulnerable to Viper's teammates without stuns.

* Fissure has a shorter cast time in Rubick's hands, making it a nice ability to either initiate or interrupt enemy ganks from a long distance.
* Though Echo Slam isn't as powerful for the lack of Aftershock on Rubick, the damage can still be massive on enemies.

* 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.

* All of Venomancer's abilities are decent choices for Rubick's Spell Steal. Stealing Plague wards makes them apply Poison sting as well.

* If Rubick steals Reaper's Scythe, he can turn the powerful ultimate back against Necrophos' team. Even his other spells are useful in Rubick's hands, giving him a sustain or a weak initiation/protection tool.

* 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.

* Rubick is a potential counter to Bounty Hunter as he can steal his Track and use it against his invisibility, and also provide his team with more gold if the tracked hero is killed.

* 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.

* Despite most Kunkka players depending on their immense physical damage, his spells provide a lot of utility for Rubick:
* Torrent is very easy to land when paired with Telekinesis.
* X Marks the Spot can potentially be more effective in Rubick's hands due to his tendency to increase his cast range with his talents and items.
* Ghostship, paired with Telekinesis, allows Rubick to land it very easily without requiring Torrent or X Marks the Spot.

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

* All of Omniknight's abilities are valuable for Rubick to Spell Steal, and Omniknight has no throwaway ability to cover his last used spell.
Additional:
* All Omniknight's abilities are perfect to steal:
* Purification can heal allies as well as damage enemies under the right circumstances. It is extremely useful since Rubick has no heal of his own.
* Heavenly Grace gives a strength bonus, status resistance, and health regeneration, which can help an ally or Rubick survive longer.
* Guardian Angel can turn the tide of battle by negating all physical damage, which is especially useful if the opposing team has physical attackers.

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

* All of Treant Protector's abilities are worth stealing, and Rubick is able to cast them with no animation time.

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

* Heroes who can 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.

* Everything she has is great in Rubick's kit:
* Crystal Nova deals crowd damage and slows enemies, also helps on farming.
* Frostbite helps Rubick locks down enemies, also is a decent farming ability.
* Freezing Field is a channeling ability and therefore can be stolen easily.
* Arcane Supremacy's Debuff Duration Amplification also benefits Crystal Nova and Frostbite greatly.

* 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.

* Heroes with strong team-fight abilities (especially ultimates) like Tidehunter, Brewmaster, Death Prophet, etc.

Additional:
* Fade Bolt reduces damage output of Anchor Smash.
* Ravage is an easy target to Spell Steal, so always be sure to use Anchor Smash immediately after Ravage when playing against a Rubick.
* Spells stolen by Rubick are potentially stronger due to the lack of cast animations, his talents, and his passive, Arcane Supremacy.

* 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.

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

* Because of her need to get status items early to tank it up, Rubick can greatly reduce her damage early with Fade Bolt
* Her stationary nature and the slow cast time of her spells makes it easier for Rubick to steal Stone Gaze or Mystic Snake
* Aghanim's Scepter's Mystic Snake is often better used by Rubick than by Medusa

* Nethertoxin prevents the lifesteal from Ransack. The silence from Viper's level 25 talent also prevents Meepo escaping with Poof.
* Meepo and his clones have a lack of magic resistance, so they're vulnerable to Poison Attack & Viper Strike directed onto one clone.

* Rubick's ability to steal Attribute Shift (Strength Gain) makes him extremely annoying to deal with because Rubick's shifted attributes will remain even if he steals a new spell.
* If Rubick moves enough points to strength and then steals Adaptive Strike, he will have a powerful 3-second ranged stun in his arsenal as well.
* Waveform provides a reliable nuke/escape to Rubick.
* Rubick can steal most abilities Morphling uses while Morphed, allowing Rubick to steal his own allies' abilities if the Morphling is not careful.
Additional:
* Morphling's abilities can cause unique interactions on their own:
* Waveform is a damaging pseudo-blink, giving Rubick much needed mobility.
* Attribute Shift (Strength Gain) is a great ability for Rubick:
* The changes done by it are permanent even after losing the ability. Pumping all the agility into strength makes him much tankier. The armor loss due to reduced agility can be mitigated by cheap items like Medallion of Courage or Solar Crest.
* The extra strength allows Rubick to survive Morphling's Ethereal Blade - Adaptive Strike (Agility) combo.
* Beware when using Attribute Shift (Agility Gain)! Unlike Morphling, Rubick does not gain damage from it, since agility is not his primary attribute.
* Adaptive Strike (Strength) is a long-ranged stun.
* The true power of this ability is revealed when Attribute Shift (Strength Gain) has been stolen previously: it gives a 4 second ranged stun every 10 seconds, which greatly counters heroes with mobility, such as Morphling himself.
* All of Rubick's abilities break Linken's Sphere, a core item for Morphling.

* 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.

* Spell Steal allows Rubick to claim Grimstroke's powerful abilities for his own, all of which are valuable.
* Arcane Supremacy increases the efficacy of stolen abilities.

* 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.

* Nethertoxin breaks the damage block from Bulwark.
* Poison Attack and Viper Strike's slows make it difficult for Mars to contribute to fights due to his low mobility.
Additional:
* Nethertoxin breaks 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.
* 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.

* In the early game, a Dragon Knight without Black King Bar is basically defenseless against Viper.
Additional:
* Dragon Knight is easily harassed by Poison Attack after the laning stage ends.
* Corrosive Skin protects Viper from Breathe Fire and returns damage.
* Nethertoxin mitigates Dragon Blood, Dragon's Knight main source of armor and health regeneration.
* Between Poison Attack and Viper Strike, Viper can keep Dragon Knight permanently slowed even in Elder Dragon Form.

* Nethertoxin prevents Timbersaw from gaining stacks on Reactive Armor with silence talent also prevents Timbersaw using his abilities.

* All his abilities is decent in Rubick's kit:
* Frost Blast allows Rubick to harass and constantly slow down enemies.
* Frost Shield increases Rubick's as well as his allies' and tower's survivability to physical attacks.
* A well-timed Chain Frost can be devastating to the enemy team.

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

* All of Winter Wyvern's spells are generally good for Rubick to steal:
* Arctic Burn provides bonus attack range, night vision and burn.
* Splinter Blast makes farming and pushing efficient while also slowing down the enemies.
* Cold Embrace can heal an ally and protect them against physical attacks.
* Winter's Curse can be stolen by Rubick and use it against herself or her own team.

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

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

* All of Invoker's abilities scales with his level, thus Rubick possesses great potential in late game by owning any of Invoker's arsenal.
* Fade Bolt counters early push from Forge Spirit.

* 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.

* Fade Bolt can hinder Jakiro's early pushing power by clearing creep waves.
* All of Jakiro's spells are great for Rubick to Spell Steal.
* Ice Path is a great spell for Rubick so steal, since Rubick has no cast time on stolen abilities, making Rubick's version of Ice Path much more reliable than Jakiro's.
* Macropyre is a great way for Rubick to farm.

* 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 over time 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 Multicast.
* Corrosive Skin minimizes the damage during Ignite and Fireblast.

* Lucent Beam is a solid magic nuke.
* Eclipse can cause massive damage if cast in the right time.
* Rubick has a good chance to steal Eclipse for Luna has only two cast abilities.
* Aghanim's Scepter greatly increased the effectiveness of the ability, including more damage as well as longer cast range. In addition, it allows him to cast it on another hero so Rubick doesn't have to get close to the enemy team in teamfights.

* Burrowstrike is one of the best and easiest steals for Rubick and Sand King should be careful when playing against him - it's much better to give away Sand Storm.

* All of Underlord's abilities are useful for Rubick to Spell Steal.

* Rubick can use Spell Steal to steal Astral Imprisonment, and if Rubick gets Aghanim's Scepter he gets 2 charges of it. This can overpower Outworld Devourer in team fights.
* Rubick can also steal Sanity's Eclipse against Outworld Devourer's teammates.

* 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.

* Because Poison Attack has a low cooldown at all levels, Aphotic Shield is ineffective as a hard dispel.
* Nethertoxin prevents Borrowed Time from activating passively and blocks Curse of Avernus

* 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.

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

* Corrosive Skin minimizes the damage from Impale and Mana Burn.
* Nyx Assassin cannot survive several poison damage-over-time, even Spiked Carapace is activated.
* However the Vendetta break can be dangerous for Viper.

* 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.

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

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

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

* Heroes with strong team-fight abilities (especially ultimates) like Tidehunter, Brewmaster, Death Prophet, etc.

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

* Heroes with strong team-fight abilities (especially ultimates) like Tidehunter, Brewmaster, Death Prophet, etc.

* 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.

* 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.

* Nethertoxin breaks Phantom Assassin's passive skills.
* Viper Strike goes through Black King Bar.

* Everything Lion has is great in Rubick's kit, further amplified by Arcane Supremacy:
* Earth Spike adds a second bit of crowd control and some damage.
* Mana Drain solves a lot of Rubick's mana issues.
* Hex is one of the strongest single-target lockdowns in the game.
* Finger of Death is one of the best magical nukes in the game.
Additional:
* All of Lion's abilities are worth stealing with Spell Steal.
* Arcane Supremacy makes the disabling spells stolen from Lion very useful, allowing you to disable enemies for an extremely long time during fights or ganks.
* By using Telekinesis, Rubick can easily catch Lion out. Without any escape mechanism, Lion is helpless, especially when ganked.

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

* Fiend's Grip is a powerful channeled ability, making it easy and useful to Spell Steal and interrupt with Telekinesis.
* Stolen Fiend's Grip or Nightmare combined with Arcane Supremacy allows Rubick to disable Bane's allies for a long amount of time.
* As a natural Aghanim's Scepter carrier, Rubick can steal an upgraded Brain Sap and deal lots of damage to Bane's team.

* Everything Enigma has is something Rubick will like:
* Malefice helps with interrupting channeling spells in case Telekinesis is off cooldown.
* Demonic Conversion helps with pushing or counter-pushing a lane.
* Midnight Pulse is great for blocking off areas or just doing steady damage in teamfights.
* Black Hole is one of the best spells for teamfights, and could easily turn a losing one around.
* Black Hole also requires channeling, making it an easy steal for Rubick because he usually stays back in a teamfight, making it hard to catch him with Black Hole.
* Telekinesis can break Enigma's Black Hole fairly easily.
* Fade Bolt counters early push strategy of Enigma's waves of Eidolons.
* Spell Steal pierces spell immunity, so Enigma can't prevent Rubick from stealing Black Hole by activating Black King Bar.
Additional:
* Telekinesis has a longer range than the AoE of Black Hole for the purposes of cancelling it.
* All of Enigma's spells are useful to Spell Steal.
* Malefice is useful for interrupting channeling spells or long cast animations.
* Demonic Conversion can be used to push or counter-push a lane.
* Midnight Pulse is useful to block an area or for team fights.
* Black Hole is very easy to steal, as it is a channeled ability. It's also one of the best ultimate abilities for team fights, and it can easily turn the fight around for the enemy team.

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

* 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.

* Every ability Witch Doctor has is useful when Rubick manages to steal any of them:
* Paralyzing Cask provides an additional disable apart from Telekinesis and also helps Rubick to farm.
* Voodoo Restoration provides utility by healing Rubick and his team, since he has no heal of his own.
* Maledict is a solid damage-over-time nuke, which can be devastating to the enemy team.
* And most importantly, Death Ward is one of the best teamfight spells in the game. It also requires channeling, which makes it easy for Rubick to steal. And when combined with Aghanim's Scepter, this can prove deadly to the enemy team.
* However, a skilled Witch Doctor will always toggle Voodoo Restoration while channeling Death Ward to prevent that.
Additional:
* Rubick can steal Death Ward easily as it is a channeled ability and then use it to turn teamfight to his advantage.
* However, a skilled Witch Doctor will toggle Voodoo Restoration immediately after placing his Death Ward to prevent that.

* 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.

* 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 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).