* Overgrowth prevents Phantom Assassin from using Blink Strike even through her spell immunity.
* Living Armor reduces Phantom Assassin's physical damage whenever she attempts to gank an allied hero.

* Living Armor and Leech Seed can be used to save a hero from a Relocate gank.
* Overgrowth can be used to cancel escape attempts with Relocate.
* Once Treant Protector buys Aghanim's Scepter, he will gain access to Eyes in the Forest, that will allow him to enchant a tree which will grant him unobstructed vision in that location, allowing him to keep his allies alerted on Io and his Tethered's attempts to gank them, and which can also allow Overgrowth to damage them and root them if they are within a 800 radius of an tree affected by Eyes in the Forest.

* Phantom Assassin does not deal with early aggression very easily (especially when magical damage). A competent Batrider can make life very difficult with Sticky Napalm followed by any other spell.

* Batrider's Flaming Lasso can be used to cancel Io's attempts to escape with Relocate and drag him away from his Tethered target. And since Io doesn't like buying Linken's Sphere, he will be always vulnerable to Batrider's initiations.
* Io's tendency to stick close to it's Tethered target can make Io and it's target vulnerable to Batrider's harrasing.
* Aghanim's Scepter upgraded Flaming Lasso allows Batrider to catch and drag two heroes at once, not just one. Which can potentially turn Io's Tether against him.
Additional:
* Batrider's Flaming Lasso can be used to cancel Io's attempts to escape with Relocate and drag him away from his Tethered target. And since Io doesn't like buying Linken's Sphere, he will be always vulnerable to Batrider's initiations.
* Io's tendency to stick close to it's Tethered target can make Io and it's target vulnerable to Batrider's harrasing.
* Aghanim's Scepter upgraded Flaming Lasso allows Batrider to catch and drag two heroes at once, not just one. Which can potentially turn Io's Tether against him.

* Many physical-only single-target heroes like Lifestealer, Sven, Wraith King, Phantom Assassin, Templar Assassin can have their damage mitigated by Cold Embrace.

* Cold Embrace can render the extra attack speed from Overcharge meaningless.
* Splinter Blast and Winter's Curse are very affective against Io, as it has to stay close to his Tethered target.

* Tinker can use Laser to save an ally or himself from Phantom Assassin's initiate Phantom Strike due to the blind, forcing her to use a Black King Bar to effectively initiate, Tinker can also use Warp Flare one he buys Aghanim's Shard to reverse Phantom Strike's blinking with Phantom Strike.
* Tinker almost never uses his physical attack, relying on his spell-spamming to deal damage which ignores Blur's Evasion
* Defense Matrix prevents Coup de Grace from triggering.

* 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.

* Phantom Assassin's single target abilities make her very helpless against swarms of Spiderlings without Battle Fury.
* Because Phantom Assassin is always reliant on critical strikes, Broodmother will usually have enough time to use Spin Web to save herself.
* Silken Bola can cripple Phantom Assassin greatly due to her being 100% reliant on physical attacks.
* Aghanim's Scepter gives Broodmother access to Spinner's Snare, which allows her to create invisible lines on her webs from Spin Web that will root Phantom Assassin, deal damage over time to Phantom Assassin and reveal Phantom Assassin if she unwittingly steps on them, disrupting her attempts to initiate or escape with with Phantom Strike while also alerting Broodmother on her attempts to ambush her and her allies.
Additional:
* Phantom Assassin's single target abilities make her very helpless against swarms of Spiderlings without Battle Fury.
* Because Phantom Assassin is always reliant on critical strikes, Broodmother will usually have enough time to use Spin Web to save herself.
* Silken Bola can cripple Phantom Assassin greatly due to her being 100% reliant on physical attacks.
* Aghanim's Scepter gives Broodmother access to Spinner's Snare, which allows her to create invisible lines on her webs from Spin Web that will root Phantom Assassin, deal damage over time to Phantom Assassin and reveal Phantom Assassin if she unwittingly steps on them, disrupting her attempts to initiate or escape with with Phantom Strike while also alerting Broodmother on her attempts to ambush her and her allies.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* Hex abilities prevent attacking, ability and item usage, which is a severe problem for Phantom Assassin as it prevents her from using Black King Bar, the one item that helps protect her against the aforementioned dangers. Doom and Shadow Demon with Aghanim's Scepter also disables Phantom Assassin's Evasion and Critical Strike, removing much of her damage and survivabaility: Doom, Disruptor with Aghanim's Scepter, Dazzle with Aghanim's Shard

* Disruptor can always Glimpse back Io or his target after he Relocated nearby.
* Even better, thanks to the indicator on the ground, you can even preemptively drop Static Storm and Kinetic Field on the spot they will relocate to.
* Thunder Strike and Glimpse are also good tools to bring back an Io that Tethered away in the fog of war.
Additional:
* Glimpse directly negates Relocate.
* Kinetic Field prevents Io from escaping with Tether.
* Static Storm can silence and damage both, Io and it's tethered target. And it can also mute both, Io and it's tethered target when upgraded with Aghanim's Scepter.

* Enfeeble greatly reduces Phantom Assassin's attack damage, and if her attack damage is weak, Coup De Grace will also suffer from attack damage reduction as well. Enfeeble also reduces cast range of Phantom Assassin's abilities, making her unable to harass with Stifling Dagger and to use Phantom Strike at longer distances.
* Nightmare and Fiend's Grip can ground Phantom Assassin, who normally blinks around with Phantom Strike, and stop her from outputting damage.
* Phantom Assassin's low health pool early on makes her susceptible to {A|Brain Sap|Bane
Additional:
* Enfeeble greatly reduces Phantom Assassin's attack damage, and if her attack damage is weak, Coup De Grace will also suffer from attack damage reduction as well. Enfeeble also reduces any healing Phantom Assassin receives, making her unable to heal herself with Phantom Strike, and it also reduces cast range of Phantom Assassin's abilities, making her unable to harass with Stifling Dagger and to use Phantom Strike at longer distances.
* Nightmare and Fiend's Grip can ground Phantom Assassin, who normally blinks around with Phantom Strike, and stop her from outputting damage, even with Black King Bar.
* Phantom Assassin's low health pool early on makes her susceptible to Brain Sap and Fiend's Grip's heavy nuke damage.

* 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.

* Slark's Pounce allows him to close the gap on Phantom Assassin and prevent her from escaping with Phantom Strike.
* As a hero who typically builds Silver Edge, Slark can use it to disable Phantom Assassin's Blur and Coup de Grace, thus taking down her attack evasion and drastically reducing her damage output.
* Because Phantom Assassin is always reliant on critical strikes, Slark will have plenty of time to escape with Pounce, Shadow Dance and Silver Edge (provided that he purchased it already).
* Depth Shroud from Aghanim's Shard will allow Slark to save both, himself and his allies from Phantom Assassin with Shadow Dance, and to freely fightback against her without removing invisibility upon attacking.
* Essence Shift is much more harmful for Phantom Assassin than for other heroes, as losing the agility means that her physical damage will be also reduced, which can also weaken Coup de Grace if Slark manages to steal lots of agility from her.
* Overall, any attempt for Phantom Assassin to take down Slark will hurt her more than Slark.
Additional:
* Slark's Pounce allows him to close the gap on Phantom Assassin and prevent her from escaping with Phantom Strike.
* As a hero who typically builds Silver Edge, Slark can use it to disable Phantom Assassin's Blur and Coup de Grace, thus taking down her attack evasion and drastically reducing her damage output.
* Because Phantom Assassin is always reliant on critical strikes, Slark will have plenty of time to escape with Pounce, Shadow Dance and Silver Edge (provided that he purchased it already).
* Depth Shroud from Aghanim's Shard will allow Slark to save both, himself and his allies from Phantom Assassin with Shadow Dance, and to freely fightback against her without removing invisibility upon attacking.
* Essence Shift is much more harmful for Phantom Assassin than for other heroes, as losing the agility means that her physical damage will be also reduced, which can also weaken Coup de Grace if Slark manages to steal lots of agility from her.
* Overall, any attempt for Phantom Assassin to take down Slark will hurt her more than Slark.

* Heroes that can easily bypass Io's allies to get to Io: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker, Lifestealer.

* Heroes with gap-closing abilities who attempt to use them for escaping Bloodseeker will suffer serious damage from Rupture: Phantom Assassin, Anti-Mage, Faceless Void, Riki, Slark, Spirit Breaker.

* Thirst allows Bloodseeker to see where Io relocated to, should either Io or the tethered hero have low health.
* Rupture forces Io to stay in place, preventing it from using the Tether bonus movement speed to escape.

* Phantom Strike's extra attack speed will cause Phantom Assassin to trigger Counter Helix more often, which can be fatal for Phantom Assassin. Jumping on Axe with Phantom Strike is not a good idea for Phantom Assassin at all as it makes her a seriously easy target for a counter-initiation with Berserker's Call and Blade Mail.
* Most of Axe's abilities pierce Black King Bar, allowing him to lock down Phantom Assassin at any time.
* Berserker's Call greatly reduces Phantom Assassin's ability to crit hard against Axe and may cause her to kill herself when used with Blade Mail. Berserker's Call can also affect Phantom Assassin even if she has Black King Bar active as Berserker's Call can fully pierce spell immunity, making Berserker's Call one of the best abilities in the game against heroes like Phantom Assassin who wants to kill opponents quickly without being interrupted.
* Culling Blade can often kill Phantom Assassin before she can do anything due to her low health and strength gain. And every time Culling Blade successfully kills Phantom Assassin or any of her teammates, Axe gains permanent armor from it, which in combination with armor items that Axe often purchases like Blade Mail, Crimson Guard, Assault Cuirass and Shiva's Guard can make Phantom Assassin's attacks only tickle Axe.
* Aghanim's Shard upgraded Counter Helix can weaken Phantom Assassin's damage output, and if her attack damage is weak, Coup De Grace will also suffer from attack damage reduction as well.
Additional:
* Phantom Strike's extra attack speed will cause Phantom Assassin to trigger Counter Helix more often, which can be fatal for Phantom Assassin in the early game. Jumping on Axe with Phantom Strike is not a good idea for Phantom Assassin at all as it makes her a seriously easy target for a counter-initiation with Berserker's Call and Blade Mail.
* Most of Axe's abilities pierce Black King Bar, allowing him to lock down Phantom Assassin at any time.
* Berserker's Call greatly reduces Phantom Assassin's ability to crit hard against Axe, and may cause her to kill herself when used with Blade Mail. Berserker's Call can also affect Phantom Assassin even if she has Black King Bar active as Berserker's Call can fully pierce spell immunity, making Berserker's Call one of the best abilities in the game against heroes like Phantom Assassin who wants to kill opponents quickly without being interrupted.
* Culling Blade can often kill Phantom Assassin before she can do anything due to her low health and strength gain. And every time Culling Blade successfully kills Phantom Assassin or any of her teammates, Axe gains permanent armor from it, which in combination with armour items that Axe often purchases like Blade Mail, Crimson Guard, Assault Cuirass and Shiva's Guard can make Phantom Assassin's attacks only tickle Axe.

* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.

* Heroes that rely on escapes to stay alive can be caught and locked down for a long time: Queen of Pain, Phantom Assassin

* Charge of Darkness can be used to escape or counter-initiate against a Relocate gank.
* Greater Bash and Nether Strike is devastating due to Io's low armor, and can even knock it away from his Tethered target.

* Heroes with heavy early and mid-game magical damage are also problematic for Phantom Assassin due to being able to easily kill her before she can gain an item advantage over them: Lina, Necrophos, Nyx Assassin, Gyrocopter, Jakiro, Death Prophet.

* Homing Missile can be used to cancel escape attempts with Relocate.
* Flak Cannon allows Gyrocopter to attack both, Io and his Tethered target, especially when upgraded with Aghanim's Scepter.
* Rocket Barrage and Call Down allow Gyrocopter to deal serious damage to both Io and his Tethered target.
Additional:
* Homing Missile can be used to cancel escape attempts with Relocate.
* Flak Cannon allows Gyrocopter to attack both, Io and his Tethered target, especially when upgraded with Aghanim's Scepter.
* Rocket Barrage and Call Down allow Gyrocopter to deal serious damage to both Io and his Tethered target.

* Hoof Stomp and Double Edge can often burst down Phantom Assassin from early to mid game.
* Retaliate makes it very unlikely for Phantom Assassin to win the lane against Warrunner. Double Edge can also be used to wear her down, as she has a much smaller health pool than that of Centaur Warrunner until purchasing a Ring of Health. Stifling Dagger will also trigger Retaliate and Blur cannot evade Retaliate.
* Centaur Warrunner's tankiness in combination with armour items that Axe often purchases like Blade Mail, Crimson Guard, Assault Cuirass and Shiva's Guard can make Phantom Assassin's attacks only tickle Centaur Warrunner.
* Centaur Warrunner just has to be careful about Fan of Knives from Aghanim's Shard and Coup De Grace, as Fan of Knives can disable Retaliate even if Centaur Warrunner is spell immune.
Additional:
* Hoof Stomp and Double Edge can often burst down Phantom Assassin from early to mid game.
* Retaliate makes it very unlikely for Phantom Assassin to win the lane against Warrunner. Double Edge can also be used to wear her down, as she has a much smaller health pool than that of Centaur Warrunner until purchasing a Ring of Health. Stifling Dagger will also trigger Retaliate and Blur cannot evade Retaliate.
* Centaur Warrunner's tankiness in combination with armour items that Centaur Warrunner often purchases like Blade Mail, Crimson Guard, Assault Cuirass and Shiva's Guard can make Phantom Assassin's attacks only tickle Centaur Warrunner.
* Centaur Warrunner just has to be careful about Fan of Knives from Aghanim's Shard and Coup De Grace, as Fan of Knives can disable Retaliate even if Centaur Warrunner is spell immune.

* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.

* Phantom Assassin's high physical damage is greatly reduced by Bulwark.
* God's Rebuke has true strike, ignoring the evasion from Blur.

* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.

* Ensnare prevents using any kind of movement abiilties, Making Naga Siren good against heroes who rely on gap-closing abilities to escape: Phantom Assassin, Magnus, Slark, Riki, Faceless Void, Storm Spirit.

* Ensnare and Song of the Siren can be used to cancel both, Tether and Relocate and to close the distance on Io.
* Rip Tide combined with illusions from Mirror Image often finish off Io before he can save himself with Tether or Relocate.
* Spirits's weak area-of-effect makes it a bad tool to deal with Naga Siren's illusions from Mirror Image.
* Once Naga Siren buys Aghanim's Scepter, she can gain access to Reel In, which not only allows her to cancel both, Tether and Relocate, but also to pull Io to herself and her team while he is affected with Ensnare, similarly to Batrider's Flaming Lasso.
* Aghanim's Shard upgraded Song of the Siren can also heal the hero Io and his Tethered targed try to gank.
Additional:
* Ensnare and Song of the Siren can be used to cancel both, Tether and Relocate and to close the distance on Io.
* Rip Tide combined with illusions from Mirror Image often finish off Io before he can save himself.
* Spirit's weak area-of-effect makes it a bad tool to deal with Naga Siren's illusions from Mirror Image.
* Once Naga Siren buys Aghanim's Scepter, she can gain access to Reel In, which not only allows her to cancel both, Tether and Relocate, but also to pull Io to herself and her team while he is affected with Ensnare, similarly to Batrider's Flaming Lasso.
* Aghanim's Shard upgraded Song of the Siren can also heal the hero Io and his tethered targed try to gank.

* Even though Phantom Assassin can easily kill Luna in few strikes, Luna can also do the same to Phantom Assassin if she is not careful.
* An ill-timed and ill-positioned Phantom Strike will make Phantom Assassin an easy target for counter-attack with Eclipse if she does not have Black King Bar available to use and if Phantom Assassin cannot kill Luna fast enough. This can be even better if Luna buys Aghanim's Scepter.
* Moon Glaives can ignore Blur's evasion if Luna attacks an enemy near Phantom Assassin.
* Luna can counter Blur's evasion by buying either Silver Edge, or Monkey King Bar, which are common items on Luna.
* Luna just has to be careful about Fan of Knives from Aghanim's Shard and Coup De Grace, as Fan of Knives can disable Moon Glaives and Lunar Blessing while Coup De Grace can deal serious damage to her even if she is spell immune, though this issue can be solved by buying Ethereal Blade, which is a situational item on Luna.
Additional:
* Even though Phantom Assassin can easily kill Luna in few strikes, Luna can also do the same to Phantom Assassin if she is not careful.
* An ill-timed and ill-positioned Phantom Strike will make Phantom Assassin an easy target for counter-attack with Eclipse if she does not have Black King Bar available to use and if Phantom Assassin cannot kill Luna fast enough. This can be even worse if Luna buys Aghanim's Scepter.
* Moon Glaives can ignore Blur's evasion if Luna attacks an enemy near Phantom Assassin. Aghanim's Shard upgraded Moon Glaives can also reduce damage from Coup De Grace and Moon Glaives Phantom Assassin inflicts on Luna and damage Spirit Phantom Assassin she is close to her. And the Aghanim's Shard upgraded Moon Glaives have true strike for their duration, which renders Blur's evasion insignificant.
* Luna can counter Blur's evasion by buying either Silver Edge, or Monkey King Bar, which are common items on Luna.
* Luna just has to be careful about Fan of Knives from Aghanim's Shard and Coup De Grace, as Fan of Knives can deal health-based damage to Luna and disable Moon Glaives and Lunar Blessing while Coup De Grace can deal serious damage to her even if she is spell immune, though this issue can be partially solved by buying Ethereal Blade, which is a situational item on Luna.

* Lucent Beam can be used to cancel both, Tether and Relocate.
* Like with Leshrac's Diabolic Edict, Lightning Storm and Pulse Nova abilities. Luna's Moon Glaives and Eclipse abilities can make short work of Io and its tethered ally, particularly when upgraded with Aghanim's Scepter.
Additional:
* Lucent Beam and 0.25s Eclipse Lucent Ministun talent for Eclipse can be used to cancel both, Tether and Relocate.
* Luna's Moon Glaives and Eclipse abilities can make short work of Io and its tethered ally, particularly when upgraded with Aghanim's Scepter.

* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* Heroes with disables that ignore spell immunity will render Phantom Assassin completely useless in teamfights throughout the game: Axe, Enigma, Vengeful Spirit, Doom, Bane, Beastmaster, Pudge, Medusa, Warlock.

* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.

* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* Heroes capable of perofrming interceptions who can anticipate and counter-initiate after Phantom Assassin blinks on them with Phantom Strike will often kill her than the other way around: Axe, Bane, Dawnbreaker, Centaur Warrunner, Luna, Medusa, Omniknight, Pudge, Razor, Terrorblade, Underlord.

* Heroes whose abilities can affect multiple enemies at once: Dawnbreaker, Ember Spirit, Lina, Luna, Jakiro, Leshrac, Invoker, Muerta, Dazzle.

* Heroes with heavy early and mid-game magical damage are also problematic for Phantom Assassin due to being able to easily kill her before she can gain an item advantage over them: Lina, Necrophos, Nyx Assassin, Gyrocopter, Jakiro, Death Prophet.

* 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 illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* In early to mid stage, Silence is also a great way to counter escape oriented heroes such as Anti-Mage, Queen of Pain, and Phantom Assassin to prevent them from escaping, provided that they don't have any basic dispels.

* Heroes that are hard to gank: Axe, Death Prophet, Phantom Lancer, Slark, Centaur Warrunner, Bristleback, Medusa, Mars.

* Heroes with disables that ignore spell immunity will render Phantom Assassin completely useless in teamfights throughout the game: Axe, Enigma, Vengeful Spirit, Doom, Bane, Beastmaster, Pudge, Medusa, Warlock.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* Heroes who rely on physical damage output to be effective will fare badly against Muerta's Pierce the Veil: Phantom Assassin, Terrorblade, Drow Ranger, Lifestealer, Anti-Mage, Alchemist, Lycan, Clinkz, Sniper.

* Heroes whose abilities can affect multiple enemies at once: Dawnbreaker, Ember Spirit, Lina, Luna, Jakiro, Leshrac, Invoker, Muerta, Dazzle.

* Doom with the {ValueColor:1|Doom applies Break|25tal} {Symbol:Talent} talent can be useful against heroes with troublesome passive skills while also disabling them for a long time: Phantom Assassin, Enchantress, Huskar, Underlord.

* Heroes with the ability to heal allies will not be able to heal heroes affected by Doom: Chen, Dazzle, Io, Oracle, Omniknight, Witch Doctor, Winter Wyvern, Abaddon, etc.

* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* Fireblast is a good tool to interrupt Io during its escapes through Tether.
* Ignite can be one of the few spells with enough total damage to out-trade the sustained healing Io provides for its fellow laner.
* However, picking other supports that focus less on the laning phase is generally a better choice against Io.

* Purification and Hammer of Purity can easily catch Phantom Assassin once she jumps with Phantom Strike in to attack.
* Heavenly Grace can be used to dispel slow from Stifling Dagger, and disables from the items Phantom Assassin relies on.
* Phantom Assassin depends entirely on physical attacks and her damage output is 100% physical. Therefore, since she has no any sources of magical damage output and hates going for items that deal magical damage like Dagon, Ethereal Blade and Revenant's Brooch, Guardian Angel will render her completely useless.
* Purification, Heavenly Grace and Guardian Angel can be used to save an allied hero before Phantom Assassin can finish them off with Coup De Grace.
Additional:
* Purification and Hammer of Purity can easily catch Phantom Assassin once she jumps with Phantom Strike in to attack.
* Heavenly Grace can be used to dispel slow from Stifling Dagger, and disables from the items Phantom Assassin relies on.
* Phantom Assassin depends entirely on physical attacks and her damage output is 100% physical. Therefore, since she has no any sources of magical damage output and hates going for items that deal magical damage like Dagon, Ethereal Blade and Revenant's Brooch, Guardian Angel will render her completely useless.
* Purification, Heavenly Grace and Guardian Angel can be used to save an allied hero before Phantom Assassin can finish them off with Coup De Grace.

* Jakiro's reliance on his abilities can cause struggles for heroes who rely on evasion or blinds to get upper hand: Phantom Assassin, Windranger, Riki, Troll Warlord, Keeper of the Light.

* Jakiro's area-of-effect ability arsenal allows him to affect multiple heroes at once, giving Io difficulties in saving them as he can only heal one hero at a time with Tether.
* Ice Path can be used to cancel both, Tether and Relocate.
* Jakiro commonly buys Rod of Atos that can be used to cancel Relocate, prevent Io in escaping with Tether and make Io easy target for Ice Path and Macropyre.
Additional:
* Jakiro's area-of-effect ability arsenal allows him to affect multiple heroes at once, giving Io difficulties in saving them as he can only heal one hero at a time with Tether.
* Ice Path can be used to cancel both, Tether and Relocate.
* Jakiro commonly buys Rod of Atos that can be used to cancel Relocate, prevent Io in escaping with Tether and make Io easy target for Ice Path and Macropyre.

* Io is a hero who needs to be close to it's tethered target to make it effective, and that's where Leshrac gets the advantage thanks to many of his area-of-effect abilities.
* Lightning Storm will usually hit both Io and its tethered target since both will be close enough for the lightning to jump.
* Diabolic Edict and Pulse Nova hit all units near Leshrac, meaning he can do colossal damage to both, Io and its tethered target.
Additional:
* Lightning Storm will usually hit both Io and his Tethered target since both will be close enough for the lightning to jump. It can then be followed up by Split Earth.
* Diabolic Edict and Pulse Nova hit all units near Leshrac, meaning he can do colossal damage to Io and his Tethered target.

* Soulbind can target both Io and its Tethered ally, allowing Grimstroke and his team to target both with single target spells. Should Io try to Relocate, Phantom's Embrace can stop its channel to prevent escape.
Additional:
* Grimstroke can catch Io and his Tethered ally easily with Soulbind as Io has a tendency to Tether himself with an ally frequently, which also makes them easier targets for Soulbind.
* Io is highly vulnerable to disables. Hence, Grimstroke's Phantom's Embrace is a great ability to hinder Io's potential.

* Puck relies mainly on magical burst damage, which Phantom Assassin is most vulnerable against.
* Phase Shift and Illusory Orb disjoint Stifling Dagger, also allowing to kite Phantom Assassin.
* Dream Coil will stun Phantom Assassin if she uses Phantom Strike to blink away.

* With Bloodthorn, Clinkz becomes a strong counter to heroes who rely on evasion and blind such as Windranger, Phantom Assassin, Troll Warlord and Keeper of the Light.

* Strafe, Tar Bomb and Burning Barrage from Aghanim's Shard allow Clinkz to quickly kill Io due to its low armor.
* Clinkz iz a hero that very often goes for Orchid Malevolence, and its upgrade Bloodthorn. Alternatively, Clinkz also loves to buy Gleipnir. And if Clinkz has both of them, he will be able to root and silence Io and prevent him from escaping with either Tether or Relocate.

* Whirling Axes (Melee) makes it hard for Phantom Assassin to land a Coup De Grace.
* Troll Warlord often buys Silver Edge and Monkey King Bar, the items that greatly help against Phantom Assassin's Blur ability.
* Battle Trance completely negates Phantom Assassin's large damage output, preventing Troll Warlord from dying easily. The lifesteal also allows Troll Warlord to restore much of his health.
Additional:
* Troll Warlord can build a Silver Edge or a Monkey King Bar to completely ignore Blur.
* Whirling Axes (Melee) provides a 60% miss chance, making a Coup de Grace critical strike very hard to land.
* Battle Trance negates Coup de Grace, preventing Troll Warlord from dying to her critical hits.

* Despite her high mobility, Hex or Earth Spike can lock Phantom Assassin down, make her vulnerable and mitigate her damage output.
* Lion relies entirely on his abilities to be effective, rendering Phatnom Assassin's high evasion through ineffective against him. And Phantom Assassin's low health pool makes her vulnerable to Lion's magical burst without Black King Bar.

* Static Link can lower the damage output from Coup de Grace procs, hindering Phantom Assassin's main source of damage. And Phantom Assassin is not a common Linken's Sphere wielder to counter this problem.
* Eye of the Storm strikes cannot be evaded by Blur.
* Both Static Link and Eye of the Storm pierces spell immunity, as Phantom Assassin is often reliant on Black King Bar.
Additional:
* Static Link can lower the damage output from Coup de Grace procs, hindering Phantom Assassin's main source of damage.
* Eye of the Storm strikes cannot be evaded by Blur.
* Both Static Link and Eye of the Storm pierces spell immunity, as Phantom Assassin is often reliant on Black King Bar.

* While Phantom Assassin can kill Skywrath Mage in a few strikes, Skywrath Mage can also do the same to her if she is not careful.
* Arcane Bolt's long range and low cooldowns allows Skywrath Mage to severely harass Phantom Assassin in lane.
* Ancient Seal prevents Phantom Assassin from escaping or engaging with Phantom Strike.
* Mystic Flare's heavy magical damage nukes Phantom Assassin down quickly during the early to mid game.
Additional:
* While Phantom Assassin can kill Skywrath Mage in a few strikes, Skywrath Mage can also do the same to her if she is not careful.
* Arcane Bolt's long range and low cooldowns allows Skywrath Mage to severely harass Phantom Assassin in lane.
* Ancient Seal prevents Phantom Assassin from escaping or engaging with Phantom Strike.
* Mystic Flare's heavy magical damage nukes Phantom Assassin down quickly during the early to mid game.

* 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.

* Morphling's naturally high armor thanks to his high agility makes it hard for Phantom Assassin to take him down with Coup de Grace.

* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.

* Terrorblade can easily take advantage of Io's weak durability with Reflection and Metamorphosis.
* As Io relies on boosting his and his Tethered target's attack speed with Overcharge, Terrorblade can take advantage of this with Reflection, which can damage and slow both, Io and his Tethered target.
* Spirits's weak area-of-effect makes it a bad tool to deal with Terrorblade's illusions from Conjure Image and Manta Style.
* Io's damage output is one of the weakest, therefore Terrorblade will have plenty of time to save himself with Sunder.
* However, Terrorblade has no way of stopping Io to escape with Tether or to stop both, Io and his Tethered target to escape with Relocate besides Terror Wave from Aghanim's Scepter.
Additional:
* Terrorblade can easily take advantage of Io's weak durability with Reflection and Metamorphosis.
* As Io relies on boosting his and his Tethered target's attack speed with Overcharge, Terrorblade can take advantage of this with Reflection, which can damage and slow both, Io and his Tethered target.
* Spirits's weak area-of-effect makes it a bad tool to deal with Terrorblade's illusions from Conjure Image and Manta Style.
* Io's damage output is one of the weakest, therefore Terrorblade will have plenty of time to save himself with Sunder.
* However, Terrorblade has no way of stopping Io to escape with Tether or to stop both, Io and it's Tethered target to escape with Relocate besides Terror Wave from Aghanim's Scepter.

* Dispersion makes it hard for Phantom Assassin to burst down Spectre while also reflecting back Phantom Assassin's high burst damage against herself.
* Black King Bar is useless for Phantom Assassin against Spectre as all of her skills pierce spell immunity.
* Spectre only needs to be careful against Fan Of Knives from Aghanim's Shard, as it can disable Desolate and Dispersion, though this issue can be solved by buying Blade Mail, which is a common item on Spectre.
Additional:
* Dispersion makes it hard for Phantom Assassin to burst down Spectre while also reflecting back Phantom Assassin's high burst damage against herself.
* Black King Bar is useless against Spectre as all of her skills pierce spell immunity.

* Quill Spray is very effective against Io, as it has very low armor and has to stay close to the fight to not break its Tether.

* Sharpshooter disables both Blur and Coup De Grace, especially with the level 25 talent.
* Because Phantom Assassin is often reliant on critical strikes, Hoodwink can have enough time to simply move near a tree and escape with Scurry.
Additional:
* Sharpshooter disables both Blur and Coup De Grace, weakening her damage and survivability.
* Because Phantom Assassin is often reliant on critical strikes, Hoodwink can have enough time to simply move near a tree and escape with Scurry.

* Phantom Assassin's Blur is useless against Windranger as she commonly buys items that require Javelin like Maelstrom, Monkey King Bar or Bloodthorn, and other than Stifling Dagger, Phantom Assassin has nothing else that can bypass Windrun.
* Additionally, Phantom Assassin doesn't like building Monkey King Bar because her crits are reliant on attack damage.
* Focus Fire can still deal considerable damage despite Blur's evasion due to the increased attack speed.
Additional:
* Phantom Assassin's Blur is useless against Windranger as she commonly buys items that require Javelin like Maelstrom, Monkey King Bar or Bloodthorn, and other than Stifling Dagger, Phantom Assassin has nothing else that can bypass Windrun.
* Additionally, Phantom Assassin doesn't like building Monkey King Bar because her crits are reliant on attack damage.
* Focus Fire can still deal considerable damage despite Blur's evasion due to the increased attack speed.

* Reactive Armor helps Timbersaw sustain harassment from Stifling Dagger.
* Phantom Assassin has a moderate health pool and usually appears in the front line of battle, making her vulnerable to Timbersaw's pure burst damage output.
* Timbersaw can easily escape from Phantom Assassin thanks to his Timber Chain.
Additional:
* Reactive Armor helps Timbersaw sustain harassment from Stifling Dagger, as well as ganking attempts.
* Phantom Assassin is a hero with moderate HP pool, and usually appears in the front line of battle. Because Blur does nothing against spells, she is vulnerable to Timbersaw's skills.
* Timbersaw can easily escape from Phantom Assassin thanks to his Timber Chain.

* Phantom Assassin relies on her Blur to stay alive, but is very vulnerable to Sand King's heavy magic damage.
* With Burrowstrike, Sand King can often catch Phantom Assassin before she can use her Black King Bar.
* Sand King can dodge Stifling Dagger with Sandstorm.
* Phantom Assassin has a hard time killing Sand King because of his high mobility.

* Laguna Blade is one of the best tools to kill Phantom Assassin before she can do anything in early-to-mid game due to its high magical (pure with Laguna Blade damage is Pure and pierces Spell Immunity talent) burst damage.
* Blur offers no protection against Lina's abilities. Likewise, Lina can counter Blur's evasion by buying either Silver Edge or Monkey King Bar.
* Lina just has to be careful about Fan of Knives from Aghanim's Shard and Coup De Grace, as Fan of Knives can deal pure damage to Lina and disable Fiery Soul awhile Coup De Grace can deal serious damage to her even if she is spell immune, which may force Lina to buy Ethereal Blade to deal with Phantom Assassin.
Additional:
* Laguna Blade is one of the best tools to kill Phantom Assassin before she can do anything in early-to-mid game due to its high magical (pure with Laguna Blade damage is Pure and pierces Spell Immunity talent) burst damage.
* Blur offers no protection against Lina's abilities. Likewise, Lina can counter Blur's evasion by buying either Silver Edge or Monkey King Bar.
* Lina just has to be careful about Fan of Knives from Aghanim's Shard and Coup De Grace, as Fan of Knives can deal pure damage to Lina and disable Fiery Soul awhile Coup De Grace can deal serious damage to her even if she is spell immune, which may force Lina to buy Ethereal Blade to deal with Phantom Assassin.

* 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.

* With Aghanim's Scepter upgraded Infest, Lifestealer can use it on enemy heroes to attack them and disarm them from inside, even if they are spell immune, which can give him the edge over the heroes he's weak against like Ursa, Phantom Assassin, Terrorblade or Troll Warlord.

* Heroes that can easily bypass Io's allies to get to Io: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker, Lifestealer.

* Hex abilities prevent attacking, ability and item usage, which is a severe problem for Phantom Assassin as it prevents her from using Black King Bar, the one item that helps protect her against the aforementioned dangers. Doom and Shadow Demon with Aghanim's Scepter also disables Phantom Assassin's Evasion and Critical Strike, removing much of her damage and survivabaility: Doom, Disruptor with Aghanim's Scepter, Dazzle with Aghanim's Shard

* Poison Touch allows Dazzle to harass both, Io and it's tethered target on lane. Aghanim's Shard upgraded Poison Touch can also hex both, Io and it's tethered target, preventing them from escaping with Relocate, and also disarming them, silencing them, muting them and rendering them helpless against Dazzle and his allies.
* Io's damage output is one of the weakest, therefore Dazzle will have plenty of time to save an ally with Shallow Grave from gank by Io and it's tethered target.
* Shadow Wave will always hit both, Io and it's tethered target if they are near the ally Dazzle uses Shadow Wave on, while healing Dazzle's allies near them. Aghanim's Scepter upgraded Shadow Wave can bounce on both, Io and it's tethered target, causing them both to take damage and to be attacked by Dazzle. And unlike Io who doesn't get healed while using Tether, Shadow Wave will always heal Dazzle no matter on which of his allies he uses it on.
* Bad Juju will cause both, Io and it's tethered target to lose armor every time Dazzle casts a spell while strengthening armor of Dazzle's allies.
Additional:
* Poison Touch allows Dazzle to harass both, Io and it's Tethered target on lane. Aghanim's Shard upgraded Poison Touch can also hex both, Io and it's Tethered target, preventing them from escaping with Relocate, and also disarming them, silencing them, muting them and rendering them helpless against Dazzle and his allies.
* Io's damage output is one of the weakest, therefore Dazzle will have plenty of time to save an ally with Shallow Grave from gank by Io and it's Tethered target.
* Shadow Wave will always hit both, Io and it's Tethered target if they are near the ally Dazzle uses Shadow Wave on, while healing Dazzle's allies near them. Aghanim's Scepter upgraded Shadow Wave allows Dazzle Shadow Wave directly on Io and it's Tethered target which can also bounce on both, Io and it's tethered target, causing them both to take damage and to be attacked by Dazzle. And unlike Io who doesn't get healed while using Tether, Shadow Wave will always heal Dazzle no matter on which of his allies he uses it on.
* Bad Juju will cause both, Io and it's tethered target to lose armor every time Dazzle casts a spell while strengthening armor of Dazzle's allies.

* Heroes such as Lone Druid, Tidehunter and Viper can be very problematic for Phantom Assassin because they give her very little time to farm and become scary.

* Fate's Edict cripples many heroes who rely on attacks, such as Phantom Assassin, Sven, or Enchantress, without a dispel or a Black King Bar.

* Any heroes with low mana pools will die quickly or even instantly to Sanity's Eclipse: Doom, Phantom Assassin, Troll Warlord.

* Heroes with disables that ignore spell immunity will render Phantom Assassin completely useless in teamfights throughout the game: Axe, Enigma, Vengeful Spirit, Doom, Bane, Beastmaster, Pudge, Medusa, Warlock.

* Heroes who just want to farm and avoid Lone Druid early will find it very hard to do so when he starts knocking on towers: Templar Assassin, Phantom Assassin, Ember Spirit, Morphling.

* With Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: Phantom Assassin, Windranger, Hoodwink.

* Heroes that rely on physical damage are ineffective against Dragon Knight due to his high armor: Phantom Assassin,Bloodseeker, Lifestealer, Troll Warlord, Sven

* Heroes whose abilities can affect multiple enemies at once: Dawnbreaker, Ember Spirit, Lina, Luna, Jakiro, Leshrac, Invoker, Muerta, Dazzle.

* Heroes with disables that ignore spell immunity will render Phantom Assassin completely useless in teamfights throughout the game: Axe, Enigma, Vengeful Spirit, Doom, Bane, Beastmaster, Pudge, Medusa, Warlock.

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

* Fragile heroes: Bounty Hunter has decent nuking capabilities with Shiruken Toss and Jinada thus making fragile heroes easy picks for ganking. Few examples of such heroes are:Crystal Maiden, Pugna, Skywrath Mage, Io, Witch Doctor, etc.

* 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 who rely on physical damage are easily negated by Ghost Shroud: Phantom Assassin, Wraith King, Juggernaut.

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

* 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.

* Hex abilities prevent attacking, ability and item usage, which is a severe problem for Phantom Assassin as it prevents her from using Black King Bar, the one item that helps protect her against the aforementioned dangers. Doom and Shadow Demon with Aghanim's Scepter also disables Phantom Assassin's Evasion and Critical Strike, removing much of her damage and survivabaility: Doom, Disruptor with Aghanim's Scepter, Dazzle with Aghanim's Shard

* Heroes who cannot prevent Sven from killing towers will often struggle from a small map very early, such as Phantom Assassin, Storm Spirit and Phantom Lancer.

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

* Heroes that can easily bypass Io's allies to get to Io: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker, Lifestealer.

* Squishy heroes (Io, Crystal Maiden, Lina...), as Earth Spirit can deal tons of damage with Magnetize.

* Heroes that can easily bypass Io's allies to get to Io: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker, Lifestealer.

* In general, Brewmaster's Cinder Brew and Thunder Clap makes him good against physical damage carries: Ursa, Clinkz, Faceless Void, Troll Warlord, Templar Assassin, Phantom Assassin.

* Heroes who can delivers a big chunk of damage in few hits will find themselves struggle against Templar Assassin's Refraction: Sven, Phantom Assassin, Ursa, Wraith King, Lifestealer

* Ice Blast prevents Io from healing an ally with Tether and prevents healing from Overcharge
* Io is a common Mekansm builder which is useless if he is affected by Ice Blast.
Additional:
* Ice Blast prevents Io from healing the target.
* Ancient Apparition can easily harass Io on lane with Chilling Touch due to it's high range and damage. This can get even worse if Ancient Apparition buys Aghanim's Scepter and combines it with items that can give him bonus attack damage and attack speed.
* Chilling Touch combined with Ice Vortex makes it nearly impossible for Io to escape from Cold Feet. Ice Vortex can also make Io and it's tethered target more vulnerable to Ancient Apparition and his allies's magical damage.

* Heroes with single-target abilities will be overwhelmed by Lycan and his summons: Wraith King, Bane, Phantom Assassin.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* Heroes with disables that ignore spell immunity will render Phantom Assassin completely useless in teamfights throughout the game: Axe, Enigma, Vengeful Spirit, Doom, Bane, Beastmaster, Pudge, Medusa, Warlock.

Additional:
* If Phantom Assassin jumps on Pudge first with Phantom Strike, she will be a very easy target for Pudge's Meat Hook and Dismember combo.
* Even though it can deal damage based on Pudge's max health, Fan of Knives from Aghanim's Shard cannot disable Pudge's Flesh Heap as Flesh Heap is one of the few passive abilities that cannot be disabled by break.
* Both Meat Hook and Dismember ignore spell immunity which allows Pudge to disable Phantom Assassin even while she has Black King Bar active.
* Pudge occassionally buys armor items like Blade Mail, which in combination with many stacks from Flesh Heap can make Phantom Assassin have little effect against Pudge.

* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* Take Aim and Assassinate allow Sniper to reach Io even if it stays in the backline.

* Heroes that can easily bypass Io's allies to get to Io: Riki, Tusk, Clinkz, Sniper, Slark, Phantom Assassin, Void Spirit, Storm Spirit, Ember Spirit, Earth Spirit, Spirit Breaker, Lifestealer.

* Heroes with high mobility can be prevented from using it to their advantage with Earthbind, even if they pack a dangerous arsenal: Earth Spirit, Ember Spirit, Storm Spirit, Nature's Prophet, Phantom Assassin, Riki, Anti-Mage, Weaver.
* See items and abilities disabled by roots

* Though certainly not a "hard counter", Crystal Maiden's skillset (magical damage nukes) does pose a substantial threat to Phantom Assassin through the mid game, especially if followed up with engagement by her team.
* A quick use of Freezing Field directly after Phantom Strike can leave Phantom Assassin trapped inside the area of effect, capitalizing on Phantom Assassin's relatively low HP pool when she is not protected by Blur, and besides Skull Basher, Phantom Assassin hates buying disabling items like Scythe of Vyse or Eul's Scepter of Divinity.
* If Phantom Assassin chooses not to buy a Black King Bar relatively early, the attack slow from Freezing Field can greatly hinder the proc chance of Coup de Grace in a teamfight.
* However, Phantom Assassin's massive damage, and her tendency to build both Black King Bar and Skull Basher makes her a formidable foe the later the game goes, and fighting her without a team is almost never a good choice.

* Lich's Chain Frost forces Io to either give up providing buff to his ally with Tether or suffer devastating damage with his Tethered ally.
* Lich can easily use Sinister Gaze to disable Io from getting away with Tether or Relocate.

* Firestorm can deal serious damage to Phantom Assassin during laning.
* Pit of Malice prevents Phantom Assassin from either escaping or engaging with Phantom Strike.
* Phantom Assassin's damage output is entirely physical, therefore Atrophy Aura is very hazardous for her in most of the stages, particularly since it also affects Coup De Grace, hindering Phantom Assassin's main source of damage.
* Without proper items and any area-of-effect ability/item, Phantom Assassin cannot stop Underlord and his team to escape with Fiend's Gate, and she has nothing to intercept Underlord and his team when they use Fiend's Gate to teleport on any area of the map outside of Fan of Knives from Aghanim's Shard.
Additional:
* Firestorm can be used to deal serious damage to Phantom Assassin during laning that ignores evasion from Blur.
* Pit of Malice prevents Phantom Assassin from either escaping or engaging with Phantom Strike.
* Phantom Assassin's damage output is entirely physical, therefore Atrophy Aura is very hazardous for her in most of the stages, particularly since it also affects Coup De Grace, hindering Phantom Assassin's main source of damage.
* Without proper items and any area-of-effect ability/item, Phantom Assassin cannot stop Underlord and his team to escape with Fiend's Gate, nor she can intercept them if Underlord chooses to teleport on any area of the map.

* Heroes which rely exclusively on right clicks will struggle somewhat against Blinding Light: Phantom Assassin, Wraith King, Medusa

* Fire Spirits applies a severe attack speed slow, severely hindering Phantom Assassin's damage output.
* Phantom Assassin cannot cast Phantom Strike on Phoenix during Supernova.
Additional:
* While her Phantom Strike does give limited extra attack speed, she cannot use the ability against the Phoenix Sun, and while her Blur may protect her from attacks, Phoenix's strong magical DPS burns away her small health pool quickly, and the attack speed slow makes her unable to fight back (provided she has no source of spell immunity).

* Duel is very effective against Io due to its low health and armor.

* 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.