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

* Sniper is completely helpless against Incapacitating Bite, and can be seriously damaged by Spiderlings in lane.

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

* Enchantress is well known for taking control of various summons with her Enchant. However, Broodmother's summons are not a good target for that, because she can swarm up a bunch of her summons with Spawn Spiderlings and Enchantress has no good waveclear (Spawn Spiderlings can also kill creeps controlled with Enchant).
Additional:
* Enchantress' lack of AoE abilities allows Broodmother to swarm her with Spiderlings.
* Spawn Spiderlings can kill enchanted creeps.

* 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.

* Chen has no area-of-effect spells to deal with Broodmother's spiderlings and must rely on his creeps to take care of them.
* Spawn Spiderlings can kill Chen's creeps and spawn spiderlings in their place.
* Spin Web allows Broodmother to disrupt Chen's jungling.
* Incapacitating Bite and Insatiable Hunger let Broodmother easily win fights against Chen.
Additional:
* Chen's low mobility and lack of AoE abilities makes him an easy target for Broodmother and her Spiderlings.
* Broodmother can easily pick off Chen's creeps with Spawn Spiderlings, and by ambushing them through terrain in her web.

* Broodmother relies less on abilities and more on right-clicks.
* Spiderlings can overwhelm Silencer, who has mediocre armor and no escape tool.

* 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 with blind of some sort can be a bad choice for Monkey King to go on: Broodmother, Riki, Keeper of the Light.

* 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.

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

* Spiderlings melt away Living Armor almost instantly.
* The vision from Eyes In The Forest may prove dangerous for Broodmother, however.

* 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.

* Support heroes with low mobility can be slowed further by Incapacitating Bite, and swarmed by Spiderlings for an easy kill: Shadow Shaman, Visage, Dazzle, Rubick, Lich.

* Phantom Assassin's single target abilities make her very helpless against swarms of spiderlings.
* Because Phantom Assassin is always reliant on critical strikes, Broodmother will usually have enough time to use Spin Web to save herself.
* Aside from Spin Web, Incapacitating Bite can cripple her due to being reliant on physical attacks and critical strikes.
Additional:
* Phantom Assassin's single target abilities make her very helpless against swarms of Spiderlings.
* Because Phantom Assassin is always reliant on critical strikes, Broodmother will usually have enough time to use Spin Web to save herself.
* Incapacitating Bite cripples her due to reliant on physical attacks.

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

* Webbed areas can be used to hit and run, covering distance hastily weakening her on the way and initiating ganks.
* Even though Medusa can hunt down Spiderlings easily when given enough range, after an Incapacitating Bite she will get her swarmed in no time.
* Medusa usual do not build a BKB to benefit from Mana Shield fully while Broodmother can fit a Diffusal Blade to burn away mana.
Additional:
* Incapacitating Bite will give Medusa a dire time to clear horde of small spiderlings or retaliate Broodmother herself.
* Spin Web will allow broodmother to pick her own fights and sometimes slip away to ambush Medusa.

* 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.

* 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.

* 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).

* 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 removes 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 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.

* 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.

* 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.

* Broodmother can kill Invoker easily in the early game with her Spawn Spiderlings and her spiderlings.
* Broodmother is both an Orchid Malevolence and a Nullifier carrier. As she can farm it early, she can kill Invoker easily.

* Drow Ranger's lack of mobility makes her easy prey for Broodmother and her Spiderlings.

* Chain Frost can bounce to the Spiderlings that Broodmother spawns.

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

* 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.

* Her Spiderlings can harass Luna in lane heavily, as Luna has no AoE abilities to clear Spiderlings.
* Broodmother can knock down towers in the early game quickly, and limit Luna's farming space.

* 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.

* 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.

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

* 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 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.

* 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.

* 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

* 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.

* 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.

* 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 summons like Broodmother,Enigma, Invoker, Nature's Prophet, Lycan, Visage;or illusions, like Naga Siren, Phantom Lancer, Terrorblade are effective at keeping the choke points and rune spawns safe from Proximity mines in the early game.

* Support heroes with low mobility can be slowed further by Incapacitating Bite, and swarmed by Spiderlings for an easy kill: Shadow Shaman, Visage, Dazzle, Rubick, Lich.

* 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.

* Oracle cannot easily deal with swarms of units, making him weak against heroes like Phantom Lancer or Broodmother.

* 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.

* Broodmother can easily clear Wraith King's skeletons with Spawn Spiderlings and summon spiderlings in their place.
* With Diffusal Blade, Broodmother can prevent Wraith King from reincarnating unless Wraith King has his Aghanim's Shard.

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

* Heroes with illusions and summons can manfight Night Stalker: Terrorblade, Beastmaster, Broodmother.

* 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.

* Broodmother can destroy Nature's Prophet's treants with Spawn Spiderlings and summon spiderlings in their place.
* Broodmother loves buying Orchid Malevolence, which can prevent Nature's Prophet from escaping with Sprout and Teleportation.
Additional:
* Sprout cannot protect Nature's Prophet if Broodmother puts down a web.
* Nature's Prophet's low mobility means he is defenseless against Incapacitating Bite.
* Spiderlings absorb much of the damage from Wrath of Nature.

* 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.

* 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.

* None of Arc Warden's skills work against Broodmother and her Spiderlings.
* Arc Warden is forced to go any lane other than mid, which he doesn't want to do, because on the lane against Broodmother he'll die over and over again.
* Broodmother is a hero best known for ending the game very early, and Arc Warden needs a couple of items to be effective.
* Arc Warden has no disables to stop Broodmother from lifestealing with Insatiable Hunger and shredding through Zet's low armor.

* 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 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 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.

* 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.

* Spin Web and Broodmother's auto-attacks allow her to gank Rubick easily before Rubick has a chance to retaliate, especially if Broodmother obtains Orchid Malevolence.
* Broodmother loves buying Diffusal Blade, which drains Rubick's low supply of mana, preventing Rubick from spamming his abilities.
* Though Insatiable Hunger is a great spell to steal, Broodmother's untargetable nature and her low cooldown spells makes it a difficult spell to steal.

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

* 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.

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

* 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.

* 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 illusions and summons can swarm Bane, who has no area abilities: Broodmother, Chaos Knight, Nature's Prophet, Phantom Lancer, Terrorblade

* Support heroes with low mobility can be slowed further by Incapacitating Bite, and swarmed by Spiderlings for an easy kill: Shadow Shaman, Visage, Dazzle, Rubick, Lich.

* 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.