* Nether Ward can punish Timbersaw, as Timbersaw is a spell-caster with low cooldowns. Furthermore, Timbersaw usually appears in the midst of battle, placing himself in range of Nether Ward's Mana Flares.
* Timbersaw has no stuns or silences to stop Life Drain. Since all of Pugna's Spells are magical, the damage can be devastating to Timbersaw.
* Decrepify can further increase all the magical damage done to Timbersaw, bypassing the enhanced physical resistance he can get from Reactive Armor.
Additional:
* Nether Ward can punish Timbersaw, as Timbersaw is a spell-caster with low cooldowns. Furthermore, Timbersaw usually appears in the midst of battle, placing himself in range of Nether Ward's Mana Flares.
* Timbersaw has no stuns or silences to stop Life Drain. Since all of Pugna's Spells are magical, the damage can be devastating to Timbersaw, especially when combined with Decrepify

* Nethertoxin prevents Timbersaw from gaining stacks on Reactive Armor.

* Nether Ward causes Death Pulse to actually damage Necrophos rather than heal him. Meanwhile, Reaper Scythe's gigantic mana cost while Necrophos is near the Nether Ward can often instantly kill him.
* Nether Blast and Life Drain both make quick work of Necrophos's small healthpool, especially during Ghost Shroud. The latter also makes him an unappealing target for Reaper's Scythe, and can often force Necrophos to use it defensively as he has no other means of interrupting his channeling.

* Viper does large amounts of magic damage over time, meaning that if a Necrophos uses Ghost Shroud, Viper's abilities will greatly reduce Necrophos survivability, and may actually kill him.
* By the same token, Viper can use his Viper Strike on Necrophos if he attempts to heal himself with Ghost Shroud, and depending on any other effects Necrophos may have from him, (IE:Poison Attack,Corrosive Skin), Viper can often kill Necrophos while he is in his Ghost Shroud.
* Viper's Corrosive Skin helps him take reduced damage from all of Nercophos spells that deal magical damage, which is Necrophos's only source of damage.
Additional:
* Nethertoxin prevents Heartstopper Aura from dealing damage or healing Necrophos.
* Viper's magic damage is amplified whenever Ghost Shroud is used.
* Corrosive Skin makes Viper tankier against Death Pulse and Reaper's Scythe.

* Nethertoxin disables Bulwark entirely, making Mars far less tanky. Using Nethertoxin inside Arena of Blood may discourage enemies from following up with Mars' initiation.
* Rod of Atos is currently common on Viper and keeps Mars in position long enough to be killed.
* Beware that Viper is not very tanky earlier in the game, so positioning against Mars is important since a well-timed Spear of Mars can be the end of Viper.
Additional:
* Nethertoxin breaks the damage block from Bulwark.
* Poison Attack and Viper Strike's slows make it difficult for Mars to contribute to fights due to his low mobility.

* Nether Blast, Decrepify and Life Drain deal high magical damage and bypasses Bulwark.
* Nether Ward reduces the amount of abilities Mars can use during fights and forces Mars to be careful about the heavy mana cost of Arena Of Blood.
* Pugna is one of few heroes that can contest Mars' ability to push and defend towers early on.

* Pugna's Decrepify can render Templar Assassin's physical attacks useless.
* Pugna can also cast Life Drain on Templar Assassin, burning her Refraction instances.
* On the other hand, Pugna generally has low health and armor. Use this to your advantage.

* The damage over time from Viper's Poison Attack and Viper Strike rapidly wear down Refraction charges, allowing Templar Assassin to be damaged. Additionally, Corrosive Skin causes her attacks to apply damage overtime on her as well.
* Nethertoxin is a big threat to Templar Assassin. Her initially low range making it very hard to deal against Nethertoxin in the laning phase. At any stage of the game, a Nethertoxin can always force her to undo her Meld.
Additional:
* All of Viper's abilities quickly burn through Refraction charges.
* Templar Assassin's short range, aside from Psi Blades' spill damage, makes her vulnerable to Poison Attack harassment.
* Templar Assassin traditionally forgoes health and armor items for damage. Outside of Black King Bar, Viper will almost always be able to kill her when Refraction is down.

* Decrepify can be used on allies to prevent them from attacking Axe and triggering Counter Helix during Berserker's Call. He can also cast it on Axe to prevent anyone from attacking him.
* Life Drain can be used to heal himself or allies caught in Berserker's Call, preventing them from dropping low enough for Axe to kill them with Culling Blade.

* Poison Attack and Viper Strike slows Axe significantly, and puts his Blink Dagger on cooldown, preventing him from initiating.
* Nethertoxin can break Counter Helix.
Additional:
* Nethertoxin prevents Counter Helix from triggering, which significantly lowers Axe's damage output in the early to mid game.
* Viper's various slows and damage over time prevents Axe from initiating as well as putting his Blink Dagger on cooldown.

* 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.

* Decrepify prevents Shadow Fiend from attacking for its duration, potentially preventing him from getting a kill.
* Nether Ward can do heavy damage to Shadow Fiend if he tries to cast his Requiem of Souls or spam Shadowraze.
Additional:
* Decrepify prevents Shadow Fiend from attacking for its duration, potentially preventing him from getting a kill.
* Nether Ward can do heavy damage to Shadow Fiend if he tries to cast his Requiem of Souls and his Shadowraze.

* Nether Blast is one of the best tower pushing abilities in the game, with a low cooldown. A competent Pugna will (at the very least) destroy tier 2 towers and make space for his team before Spectre can finally come online.
* Spectre's spells, while not spammable, have a fairly high mana cost, so Nether Ward can be fairly damaging to Spectre early game. The mana degen will also dampen Spectre's early game power significantly.
* Once Pugna gets Aghanim's Scepter, he can spam Life Drain on any illusion Spectre summons, whether it'd be from Haunt, Manta Style, or some other means.
* In addition, Pugna can disable Spectre's Desolate ability (although its damage is pure, it requires physical attacks) with his Decrepify ability, leaving Spectre only with Spectral Dagger.

* 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.

* Even though Pugna's low HP means that he can be quickly burst down, his Nether Ward heavily punishes casters whose spells cost a lot of mana, like Zeus. Casting 4 of his active spells, including Nimbus, close to an enhanced level 4 Nether Ward, can make the ward deal up to 1750 magical damage.
* Decrepify can further increase the damage dealt by Nether Ward upon Zeus. However, if used on Pugna himself or on one of his allies, it will amplify the damage done by Zeus' abilities.

* 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.

* Nether Ward can do a ton of damage to Disruptor because of his high mana costs.
* Life Drain can be used to heal an ally trapped by Static Storm-Kinetic Field combo (if Pugna is not a target).

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

* Nether Blast will still hit Slark in Shadow Dance.
* Pugna can rarely target Slark directly with Decrepify, but he can use it defensively on an ally to prevent Slark from getting stacks.
* Despite being somewhat easy to break with Pounce, Pugna can damage Slark and provide vision over him with Life Drain.

* 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).

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

* Amazingly, Enchantress has even lower health than Pugna. Though she does pack quite a punch through Impetus, she can't use it if she is under Decrepify.
* Pugna's Magical DPS is way greater than the heal from Nature's Attendants, which will also harm her quite a bit if she's next to Nether Ward.

* Nether Ward will be problematic for heavy nukers and spammers like Skywrath Mage, Lina, Lion and Invoker, but don't use Decrepify defensively against them as you'll be helping them out more than anything.

* 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.

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

* Troll Warlord can't switch targets at will, in order to build Fervor stacks, which makes it easy to use Decrepify in order to save allies
* During Battle Trance, Pugna can easily use Nether Blast, Decrepify and Life Drain on him

* 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.

* Any hero who can counter-initiate in anticipation without getting caught in Reverse Polarity: Sven, Omniknight, Enigma, Luna, Naga Siren, Mars, Jakiro, Venomancer, Elder Titan, Faceless Void, Rubick, Keeper of the Light, Pugna, Invoker, Spectre, Alchemist, Treant Protector, Lina, Oracle, Zeus, Shadow Shaman, Phoenix, Razor, Huskar, Batrider, Kunkka, Tidehunter, Wraith King, Sand King.

* Pugna can save allies with both healing or by making them ethereal but needs to be careful of Sven's Aghanim's Scepter purge.

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

* 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.

* Any hero that can outrange Plague Ward can neutralize them without putting themselves at risk of receiving Poison Sting: Arc Warden, Chen, Clinkz, Drow Ranger, Lina, Mirana, Nature's Prophet, Pugna and Sniper.
* Special mention to heroes that outrange Plague Ward after obtaining talents that increase attack range.

* 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.

* Heroes who are reliant on physical damage will be nullified by Decrepify: Riki, Wraith King, Juggernaut.

* Pugna's Decrepify makes sure that either Alchemist is unable to hit anyone while also being slowed and susceptible to magical damage, or can protect an ally from physical attacks. Besides, Pugna can push early on, when Alchemist is not strong enough to repel it, so by the time Alchemist comes online, he might be forced to sit in base.

* 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 damage burst can often kill Chen or his allies before he can use Hand of God: Lina, Techies, Shadow Fiend, Pugna, Nyx Assassin.

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

* Dragon Knight is easily harassed by Poison Attack after the laning stage ends.
* Corrosive Skin protects Viper from Breathe Fire and returns damage.
* Nethertoxin mitigates Dragon Blood, Dragon's Knight main source of armor and health regeneration.
* Between Poison Attack and Viper Strike, Viper can keep Dragon Knight permanently slowed even in Elder Dragon Form.
Additional:
* In the early game, a Dragon Knight without Black King Bar is basically defenseless against Viper.
* Viper can harass Dragon Knight at any time with his Poison Attack.
* Corrosive Skin reduces damage from Dragon Fire and inflicts damage to him.
* Nethertoxin disables Dragon Blood, negating his main survivability.
* Viper Strike and Poison Attack can severely slow him down even with his Elder Dragon Form.

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

* 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.

* All of Pugna's abilities are active, making Demonic Purge break from Aghanim's Scepter useless.
* Nether Ward punishes Shadow Demon's constant mana usage from spamming spells, especially Shadow Poison.
* An attempt to save an ally using Disruption can easily become a perfect setup for a Nether Blast for the enemy.
* Life Drain can be used to heal Pugna or an ally to save them from Shadow Demon's abilities.
* However, it can be cancelled by Disruption unless Pugna buys defensive items.

* 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.

* 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.

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

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

* 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.

* Because Invoker relies on casting a large amount of spells to contribute to fights, Nether Ward can force him to not cast anything at all or take a large amount of damage to cast spells.
Additional:
* Nether Ward on its own can greatly hinder Invoker from casting many of his abilities, at least until he gets a significant amount of HP or is under the protection of spell immunity from Black King Bar
* Life Drain provides True sight, revealing Invoker through Ghost Walk, and forcing him or his allies to use an ability or item to interrupt its channeling
* Outside of Nether Ward's range, Invoker shall have the advantage, as Invoker has Tornado to purge Pugna's Decrepify when it is used defensively, Tornado or Cold Snap to prevent Pugna from channeling Life Drain
* A poorly used Decrepify on Pugna's allies means Invoker's abilities can be used to deal more damage to them.

* Decrepify prevents Faceless Void from attacking trapped allies inside Chronosphere, wasting a large portion of its duration if Faceless Void can't dispel it.

* 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.

* 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.

* Cold Embrace is a death sentence against Pugna, since its the perfect setup for all his abilities, especially Life Drain.
* Decrepify can be cast to save the ally under Winter's Curse effect, wasting most of its duration.
* Winter Wyvern's abilities require a lot of mana, allowing Nether Ward to deal lots of damage.

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

* Nethertoxin disables Dawnbreaker's Luminosity|Dawnbreaker. Since she's a melee hero, she needs to close gap to attack and Nethertoxin will be bad for her since she cannot heal.
* Viper Strike and Poison Attack will severely slow her down and combined with Nethertoxin, it will be her death sentence (unless her Celestial Hammer or Solar Guardian are off cooldown). Besides that, chasing her down will be easy due to the slow.

* Decrepify prevents Omnislash damage, until Juggernaut gets a Nullifier.
* Without a disable, Pugna's high movement speed makes it harder to chase him with Blade Fury.
* Juggernaut has low mana and his skills cost large amount of mana. Nether Ward will hurt him more and even worse, the damage from the ward is inflicted before the Spell immunity provided by Blade Fury.
Additional:
* Decrepify is the perfect tool against Omnislash until he gets a Nullifier, and even then he will probably waste a couple of slashes before he uses it.
* Without an extra disable, Pugna's high movement speed makes it impossible to chase him with Blade Fury.
* Unlike some other carries like Slark or Phantom Assassin, Juggernaut's spells cost a hefty amount of mana and he will seriously get hurt by Nether Ward. Don't forget the damage from the ward is inflicted before the spell immunity is provided by Blade Fury.

* Due to the high mana cost of his spells and the low cool down of them, Nether Ward can seriously damage Skywrath Mage if he isn't careful.
* Skywrath Mage's fragility makes him very susceptible to Pugna's high burst damage.
Additional:
* Nether Ward will make Skywrath Mage next to useless in fights, as his low hp pool will not allow him to sustain through the damage of the ward should he choose to cast spells. Be wary though that Skywrath's huge burst will make very quick work of Pugna's low hp should the ward be destroyed, and Decrepify won't help you at all.

* Because Poison Attack has no cooldown, Aphotic Shield is ineffective as a hard dispel.
* Nethertoxin prevents Borrowed Time from activating passively and blocks Curse of Avernus

* Nethertoxin disables Vengeance Aura.
* Vengeful Spirit has no mobility spells aside from Nether Swap, which Viper can take advantage of with his slows.
* Viper can easily bully Vengeful Spirit out of a lane with Poison Attack.
Additional:
* Nethertoxin prevents the attack damage bonus from Vengeance Aura and the components of Nether Swap.
* Both Magic Missile and Wave of Terror are counteracted by Corrosive Skin, making Vengeful Spirit's fighting harder against Viper.

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

* Leshrac needs to be close to target in order to do damage, Pugna can outrun Leshrac with ease due to his superior movement speed.
* Split Earth can also be hard to land on Pugna for the same reason.
* Leshrac uses huge amounts of mana to do damage, Nether Ward forces him to either not contribute in a fight or kill himself in the process.
Additional:
* Nether Ward punishes Leshrac's constant mana usage from spamming spells.
* Leshrac needs to be in the thick of the fight to deal damage, and so cannot escape from Nether Blast nor Life Drain easily.

* 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.

* Nether Ward discourages Tinker from using abilities and items due to its high damage against heavy mana usage.

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

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

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

* 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 movement speeds like Pugna and Meepo can run around, to, or away from Snapfire during Mortimer Kisses and dodge the projectiles easily due to their slow speed.
* Heroes with mobility spells (such as Queen of Pain's Blink and Clockwerk with Hookshot) can easily avoid Lil' Shredder and Mortimer Kisses.
* Heroes with high movement speeds like Pugna and Meepo can run around, to, or away from Snapfire during Mortimer Kisses and dodge the projectiles easily due to their slow speed.

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

* Any heroes with high intelligence, such as Invoker and Pugna.

* Heroes that can punish aggressive heroes, such as: Leshrac, Shadow Demon, Pugna, Death Prophet.

* 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.

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

* Pugna: Decrepify prevent the Spirit bear from attacking or protect allies from it.

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

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

* 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.

* 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.

* Nethertoxin prevents the lifesteal from Ransack.
* Meepo and his clones have a lack of magic resistance, so they're vulnerable to Poison Attack & Viper Strike directed onto one clone.

* Enigma's abilities have a huge mana cost, meaning that Nether Ward will deal a lot of damage to Enigma.
* Pugna can heal allies trapped inside Black Hole thanks to Life Drain.
* Nether Blast can easily kill Eidolons, especially when Enigma is pushing.

* Arc Warden can't use Magnetic Field to stall the damage of Nether Blast on towers, but he can buy Aghanim's Shard 20 minutes into the game to diminish its damage
* Arc Warden has no innate disables to stop Life Drain and Decrepify
* The short cooldown of both Life Drain and Decrepify also means Pugna can deal with Arc Warden and Arc Warden's clone simultaneously most of the time
* A good Pugna looks to end the match early while Arc Warden, a very item reliant hero, thrives in longer matches.

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

* Heroes who are reliant on physical damage will be nullified by Decrepify: Riki, Wraith King, Juggernaut.

* Nether Ward will be problematic for heavy nukers and spammers like Skywrath Mage, Lina, Lion and Invoker, but don't use Decrepify defensively against them as you'll be helping them out more than anything.

* Pugna's Nether Ward damages Sand King when he channels Epicenter, preventing him from using Blink Dagger afterward.

* Decrepify prevents Legion Commander from attacking allies during Duel, regardless if it's used on her or on the ally .
* Pugna can easily cast Decrepify, Nether Blast and Life Drain on Legion during the 4/4.75/5.5/8 seconds of duel
Additional:
* Decrepify on either hero stops Legion Commander from completing a Duel, and dissuades her from initiating Duels on ethereal allies.
* Life Drain can help Pugna's teammates win a fight, either by killing Legion Commander or replenishing her target's health.

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

* 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.

* Pugna's Decrepify prevents the target from taking physical damage or doing damage, which poses a huge problem for Lycan, as he mainly deals physical damage.