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

* 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.

* 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.

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

* 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.

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

* 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

* 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.

* 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.

* 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.
* Activate Fire Remnant and Sleight of Fist allows Ember Spirit to dodge Charge of Darkness if timed correctly.

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

* 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.

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

* 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.

* 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.

* 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 boosted by Battle Fury and Daedalus makes quick work of Meepo if clones are crowded around each other.
* Searing Chains interrupts Meepo's initiating because Meepo's clones do not have spell immunity.

* 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.

* 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.

* 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.

* 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 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.

* Corrosive Skin counters Zeus in lane by canceling the effects of Clarity as Zeus relies on Arc Lightning to farm and secure last hits.
* Corrosive Skin also increases Viper's magic resistance to shrug off Zeus's magical nukes.
* Nethertoxin breaks Static Field.
* Due to Zeus' poor mobility, Viper Strike will cripple Zeus and will allow Viper and his teammates to land a lot of attacks.
Additional:
* Corrosive Skin severely reduces Zeus's damage output throughout the game.
* During the laning stage, Viper can abuse Zeus' reliance on spells by hugging the creep wave. Zeus will take constant damage over time from Corrosive Skin unless he drives Viper from the lane or returns to farming in his absence.
* Prior to buying Blink Dagger or Force Staff, Zeus is fragile and possesses low mobility. Any of Viper's numerous slows can set up an easy kill.

* Nethertoxin 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.

* 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.

* 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.
* Ember Spirit usually builds Eul's Scepter of Divinity to dispel Soul Catcher and Linken's Sphere to block Disruption and Demonic Purge.
* The best you can do against an Ember Spirit is to dispel his Flame Guard with your Demonic Purge.

* 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.

* 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).

* 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.

* 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.

* 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.

* 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.

* Nethertoxin cancels out Kraken Shell and stops the hard dispel from passively activating, preventing Tidehunter from functioning as a frontline tank.
* Anchor Smash is mostly irrelevant against a ranged hero.
* Tidehunter relies on the threat of Ravage, which has an obscenely long cooldown. Viper can exploit the downtime with his short cooldowns.

* Nethertoxin 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.

* 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.

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

* 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

* 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.

* 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.

* 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.

* 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.

* 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.

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

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

* Heroes who can dodge Earth Spirit's abilities: Ember Spirit, Puck, Weaver

* 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 work, they can adjust their movement to avoid it entirely and of course outplay the Pangolier player.

* 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 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.

* 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 deals considerable magical damage to Windranger.

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

* 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 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 of his Treants and getting lots of gold.
* Ember Spirit with Fire Remnant and Boots of Travel can teleport and defend tower whenever Nature's Prophet tries to push.
Additional:
* 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.

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

* 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.

* 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 range, ignoring Upheaval, and Searing Chains lets him interrupt it.

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

* 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.

* 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.
* 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, which are the only solutions to deal with Ember 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.

* 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.
Additional:
* Sleight of Fist is the natural counter to Phantom Lancer's army of illusions, especially when combined with Battle Fury.

* 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.

* 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.

* 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.

* 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.

* 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.