* 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.

* Flame Guard absorbs up to 500 magical damage (700 with Level 10 talents), which helps Ember Spirit survive against Storm Spirit's high magical damage.
* Searing Chains can root enemies up to 3 seconds, making Storm Spirit unable to escape with Ball Lightning.
* Fire Remnant deals high magical damage when casting multiple instances at once, granting Ember Spirit the damage to burst Storm Spirit down in the early to mid game.

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

* Heroes who commonly buy Linken's Sphere: Luna, Weaver, Morphling, Queen of Pain, Ember Spirit.

* Heroes with damage-increasing passive abilities, such as Viper and Riki, will usually kill Silencer in a short time before he even has time to set up his abilities.

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

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

* Certain Hero's potential lies on the combo of their abilities. As an example, Ember Spirit can cast Sleight of Fist and Searing Chains together to root and damage enemies from a far distance. Yet for Rubick, casting Searing Chains can only catch enemies at a close distance, and Sleight of Fist does little more than a scratch of right click.
* It is arguably possible to group spells together after getting Aghanim's Scepter, but stealing two separate spells from one single enemy is somewhat luxurious in an intense fight.

* Heroes that heavily depend on illusions or summons, (Naga Siren, Terrorblade, Phantom Lancer, Lycan,...) are vulnerable to Sleight of Fist and even more so if Ember Spirit has Battle Fury.

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

* 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.

* 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.

* Ember Spirit absorbs quite a large amount of magical damage with its Flame Guard, and in addition dodges the abilities of Dragon Slave and Light Strike Array with its Sleight of Fist
Additional:
* Ember Spirit absorbs quite a large amount of magical damage with its Flame Guard, and in addition dodges the abilities of Dragon Slave and Light Strike Array with its Sleight of Fist.

* Viper Strike prevents Timbersaw from gaining stacks on Reactive Armor.

* Searing Chains prevents usage of Timber Chain.
* Timbersaw is vulnerable to magical burst damage, which Ember Spirit provides with Fire Remnant and Flame Guard.
* Timbersaw's abilities deal pure damage, thus they cannot remove Flame Guard.

* 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.

* Ember Spirit can close the distance between Sniper easily with his Activate Fire Remnant and further keep Sniper in place with Searing Chains.
* With the help of Aghanim's Scepter, Sniper cannot outrun Ember Spirit or chase him, even if Sniper builds mobility items.

* 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.

* Zeus laneing against Ember is going to be punished with Sleight of Fist due to his low health pool
* Zeus's chip damage from Arc Lightning and other spells is nullified from Ember's Flame Guard.
Additional:
* Ember Spirit has a built-in antimagic shield, and Zeus has nothing but this magical damage, because of this, their confrontation on the center line can turn out to be sad for Zeus. If on such a line Ember Spirit will finish off all creeps under its Flame Guard, and Zeus with the help of Arc Lightning, then eventually Zeus will lose mana faster, and will be forced to look for ways to replenish it
* Ember Spirit can interrupt Zeus with his "jumping" abilities, the fact is that Zeus deals damage from his abilities directly, while Ember Spirit disappears for milliseconds from the battlefield when flying during the Sleight of Fist action or when flying into Fire Remnant

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

* Ember Spirit has much higher mobility in Fire Remnant than Void Spirit.
* Ember's Flame Guard is effective against Void Spirit's spells, as most of them deal magical damage.
* The root from Searing Chains prevents Void Spirit from using Dissimilate or Astral Step.

* 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.

* Searing Chains and Flame Guard quickly burn through Refraction instances exposing her low health pool.
* Templar Assassin has no inherent way to prevent Ember Spirit from escaping, a good Ember player also will be able to dodge her meld attack
* Ember Spirit`s Searing chains give true sight into invisibility, why Templar Assassin can't hide from it in Meld and get out of the fight using Blink Dagger
Additional:
* Flame Guard burns quickly through Refraction charges, which is why it can interrupt Templar Assassin, giving his team the opportunity to kill her.
* Ember Spirit can dodge a blow from Meld with Sleight of fist, providing him an advantage in a 1v1 situation.
* Searing Chains give true sight into invisibility, why Templar Assassin can't hide from it in Meld and get out of the fight using Blink Dagger.

* 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.

* Any hero with teleport abilities (e.g. Ember Spirit, Storm Spirit) can easily break Static Link.

* 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.

* Crystal Maiden is extremely fragile and she's an easy target for him. She has no real disables that can lock Ember Spirit down, and all of her skill damage can be negated with Flame Guard. The damage from Searing Chains, Flame Guard, and Sleigh of Fist can easily take her down.

* 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.

* Ember's magic damage build is able to burst down Alchemist due to his low strength gain and Alchemist's normal item pick up.

* Heroes that can slow Charge of Darkness by a huge amount: Venomancer, Viper, Dazzle, Arc Warden, Lion, Huskar, Shadow Shaman, Visage, Undying, Jakiro.

* Searing Chains can stop Charge of Darkness if timed correctly.
* Activate Fire Remnant can be used to escape an approaching Spirit Breaker, or lead Spirit Breaker into a bad situation.
* Fire Remnant and Sleight of Fist allows Ember Spirit to dodge Charge of Darkness if timed correctly.

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

* Ember Spirit with Sleight of Fist and Activate Fire Remnant
* Heroes that can dodge Glimpse:
* Puck with Phase Shift
* Riki with Tricks of the Trade
* Phantom Lancer with Doppelganger
* Ember Spirit with Sleight of Fist and Activate Fire Remnant
* Chaos Knight with Phantasm
* Naga Siren with Mirror Image
* Tusk with Snowball
* Juggernaut with Omnislash
* Brewmaster with Primal Split
* Lifestealer with Infest
* Phoenix with Supernova

* 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.

* Meepo is quite fragile in the early game and can be easily taken down by Flame Guard's and Searing Chains' damage. Later on, Meepo is very vulnerable to Sleight of Fist's damage due to Battle Fury's cleave on multiple Meepos.
Additional:
* Sleight of Fist combined with Battle Fury, Maelstrom and Daedalus will allow Ember Spirit to make a quick work of Meepo if his clones are crowded around each other.
* Searing Chains interrupts Meepo's initiating because Meepo's clones do not have spell immunity.

* 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 easily bypass Chen's creeps to get to Chen: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker.

* 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.

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

* Nethertoxin breaks 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.

* 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.

* 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.

* 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.

* Disruption is not reliable enough to catch an Ember Spirit with a backup Fire Remnant.
* Sleight of Fist will also make quick work of the spawned illusions.
* The best you can do against an Ember Spirit is to dispel his Flame Guard with your Demonic Purge.

* 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.

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

* 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.

* Flame Guard blocks Dark Willow's magical burst damage, and harms her if she tries to get close to attack with Bedlam.
* Sleight of Fist and Fire Remnant makes it hard for Dark Willow to fully disable Ember Spirit.

* Ember Spirit easily finishes off all creeps on the line against Earth Sprit, exchanging health with him under his Flame Guard, which is why Earth Spirit can leave the line for ganks very early and without the necessary amount of gold and levels, which will give the Ember Spirit team an advantage to fight off such ganks
* The Sleight of Fist ability helps Ember Spirit dodge all of Earth Spirit's abilities, which makes his gank potential practically useless against Ember Spirit, and with the purchase of Black King Bar, Ember Spirit can use Sleight of Fist to combine with Searing Chains to catch and kill Earth Spirit.
Additional:
* Ember Spirit easily finishes off all creeps on the line against Earth Sprit, exchanging health with him under his Flame Guard, which is why Earth Spirit can leave the line for ganks very early and without the necessary amount of gold and levels, which will give the Ember Spirit team an advantage to fight off such ganks
* The Sleight of Fist ability helps Ember Spirit dodge all of Earth Spirit's abilities, which makes his gank potential practically useless against Ember Spirit, and with the purchase of Black King Bar, Ember Spirit can use Sleight of Fist to combine with Searing Chains to catch and kill Earth Spirit.

* 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.

* Fire Remnant allows Ember Spirit to escape while Ruptured.
Additional:
* Fire Remnant allows Ember Spirit to escape Bloodseeker while Ruptured.

* 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.

* 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'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.

* 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.

* 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 Strike is a strong and breaks Fury Swipes, undispellable slow, making it much easier to kite Ursa for everyone.

* 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.

* 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.

* Ember Spirit's Fire Remnant is an easy way to escape from Clockwerk's Power Cogs.
* Flame Guard blocks most of the magical damage Clockwerk does.

* 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.

* Corrosive Skin minimizes the damage Viper takes from all of Ancient Apparition's abilities.
* Ancient Apparition's slow movement speed, squishy nature, and lack of escape abilities can easily be taken advantage of through Poison Attack and Viper Strike.

* Nethertoxin 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 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.

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

* 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.

* The high mobility provided by Fire Remnant makes it hard for Windranger to find a good position to land Shackleshot or a full duration of Focus Fire.
* Flame Guard and Searing Chains deal considerable magical damage to Windranger which she cannot avoid with Windrun.
* Searing chains also negates the mobility from Windrun.

* Heroes with high physical and magical damage alike are a huge hazard for Muerta, as they can deal serious damage to her even if she has Pierce the Veil active: Luna, Lina, Tusk, Broodmother, Shadow Fiend, Ember Spirit, Gyrocopter, Vengeful Spirit, Arc Warden, Medusa, Shadow Shaman.

* Heroes with strong area-of-effect damaging and/or disabling abilities will be able to intercept Underlord and his team when they exit from Fiend's Gate: Luna's Aghanim's Scepter upgraded Eclipse, Dawnbreaker's Solar Guardian, Axe's Berserker's Call, Mars's Arena of Blood, Jakiro's Macropyre, Dual Breath and Ice Path, Naga Siren's Song of the Siren, Razor's Eye of the Storm and Plasma Field, Lina's Light Strike Array, Broodmother's Spinner's Snare from Aghanim's Scepter, Elder Titan's Earth Splitter and Echo Stomp, Alchemist's Unstable Concoction and Acid Spray, Queen of Pain's Sonic Wave, Dark Seer's Wall of Replica and Vacuum, Venomancer's Noxious Plague and Poison Nova from Aghanim's Scepter, Oracle's Fortune's End and Rain of Destiny from Aghanim's Shard, Bloodseeker's Blood Rite, Enigma's Black Hole and Midnight Pulse, Shadow Fiend's Requiem of Souls, Batrider's Aghanim's Scepter upgraded Flaming Lasso, Firefly, Flamebreak and Sticky Napalm, Ancient Apparition's Ice Blast, Sand King's Epicenter, Sand Storm and Burrowstrike, Gyrocopter's Call Down, Ember Spirit's Sleight of Fist, Death Prophet's Exorcism and Silence, Monkey King's Wukong's Command, Crystal Maiden's Freezing Field, Muerta's The Calling, Medusa's Stone Gaze, Zeus's Nimbus from Aghanim's Scepter. Dark Willow's Bramble Maze, Pangolier's Swashbuckle, Grimstroke's Soulbind, Ink Swell and Stroke of Fate, Earthshaker's Echo Slam and Fissure, Puck's Dream Coil and Waning Rift, Winter Wyvern's Winter's Curse, Magnus's Reverse Polarity.

* Heroes with considerable mobility can easily escape from a rolling Pangolier: Anti-Mage, Queen of Pain, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, moreover, if a player is familiar with how Rolling Thunder works, they can adjust their movement to avoid it entirely and of course outplay the Pangolier player.

* Heroes that can reliably kite out Dispose, Unleash and dodge Rebound, like Ember Spirit, Void Spirit, Storm Spirit, Anti-Mage, Faceless Void, Puck or always build items like Blink Dagger and Force Staff.

* 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.

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

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

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

* Heroes with high mobility will be able to avoid Gyrocopter's area attacks: Storm Spirit, Morphling, Ember Spirit

* 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).

* Heroes with a high degree of mobility and invisibility are hard to catch with Meat Hook: Ember Spirit, Riki, Clinkz, Queen of Pain.

* Heroes with good mobility to avoid Jakiro's abilities and with good chase to punish Jakiro from pushing a tower: Bloodseeker, Ember Spirit, Juggernaut, Phantom Assassin, Weaver.

* 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.

* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Jakiro, Viper, Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.

* Heroes with either magical, physical or pure damage burst: Bane, Ember Spirit, Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, Ursa, Void Spirit.

* Heroes with escaping and disjointing abilities can be good against Juggernaut:Anti-Mage Riki, Queen of Pain, Puck, Storm Spirit, Ember Spirit, Slark etc.

* Ember Spirit can easily deal with Nature's Call by using his Flame Guard and with Battle Fury. He also has multiple ways of escaping Sprout. Additionally, Ember Spirit can break Sprout's trees with Activate Fire Remnant and interrupt Teleportation with Searing Chains.
Additional:
* Sleight of Fist with Battle Fury deals a lot of damage to Nature's Prophet's team if they stand close to his Treants, as well as killing all the Treants with ease.
* Ember Spirit with Fire Remnant and Boots of Travel can be very active around the map, which enables him to quickly teleport and defend the objective Nature's Prophet is attacking whenever he tries to push.

* A pre-placed Fire Remnant allows Ember Spirit to escape Upheaval.
* Flame Guard blocks Shadow Word's damage.
* Sleight of Fist allows Ember Spirit to attack from outside of Upheaval's range, and Searing Chains lets him interrupt it.

* 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

* Flame Guard makes Dark Seer not deal any damage with his skills to Ember Spirit.

* Heroes with Attack speed decreasing skills: Jakiro, Viper Lich

* Heroes with strong area damage to destroy Phantasm illusions: Axe, Ember Spirit, Legion Commander, Phoenix

Additional:
* Ember Spirit is evasive and can dodge close encounters with melee heroes like Chaos Knight. Ember Spirit can't be caught with the slow from Reality Rift, and Flame Guard and Sleight of Fist can bring Phantasm's illusions down quickly.

* 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.

* Sleight of Fist is the natural counter to Phantom Lancer's army of illusions, especially when combined with Battle Fury.
Additional:
* Sleight of Fist, allows Ember Spirit to destroy all of Phantom Lancer's illusions.
* Flame Guard also deals significant damage to illusions, and protects against Spirit Lance.
* Phantom Rush is unable to catch Ember Spirit when he teleports to his Fire Remnants.

* 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.

* Ember Spirit can deal devastating damage to illusion heroes like Terrorblade with Sleight of Fist. Terrorblade also has no way of preventing Ember Spirit from getting Activate Fire Remnant off. Additionally, Ember Spirit's ability to fight from long range as well as his wide skill set won't give many opportunities for Terrorblade to get Sunder off.
Additional:
* Ember Spirit can deal devastating damage to Terrorblade and his illusions with Sleight of Fist, Flame Guard and Fire Remnant.
* Terrorblade has no disable to lock down Ember Spirit and prevent him from escaping with Fire Remnant. In addition, he doesn't like purchasing disabling items like Scythe of Vyse or Abyssal Blade, which are the only solutions to deal with Ember Spirit.

* Heroes that heavily depend on illusions or summons, (Naga Siren, Terrorblade, Phantom Lancer, Lycan,...) are vulnerable to Sleight of Fist and even more so if Ember Spirit has Battle Fury.

* Sleight of Fist keeps Ember Spirit invulnerable until he hits every unit in its area of effect allowing him to stall for large amounts of time against Broodmother and her large amounts of spiderlings, or potentially damaging them enough if equipped with an item to improve wave clearing such as Battle Fury or Maelstrom to prevent her pushes entirely.
* Flame Guard will damage any of Broodmother's spiders in an area, deterring her from attempting to kill him. It can also be used during Sleight of Fist to amplify damage done.
* Fire Remnant allows Ember Spirit an escape from Broodmother that is unaffected by her Incapacitating Bite.

* 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.