* 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.

* Cold Embrace can protect Troll Warlord's target, especially during Battle Trance.
* Winter's Curse can turn Troll Warlord's high physical damage and attack speed against his allies.
Additional:
* Cold Embrace will protect your ally from being damaged if he gets focused by Troll, although be careful as Fervor will keep gaining stacks even while Cold Embrace is active.
* Fervor works on allies.
* His high attack speed will help to kill his cursed ally faster.

* 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.

* Frost Blast and Chain Frost can kite Troll Warlord effectively.
* Frost Shield can single-handedly waste most of the duration of Battle Trance, due to the extreme resistance to physical damage Frost Shield provides. In addition, Troll Warlord is incapable of switching targets during Battle Trance, so he cannot pick an easier target.
* Troll Warlord has little to no ability to regenerate HP, so Frost Blast together with Frost Shield can harass him effectively.

* 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.

* Clinkz, Sniper, Lone Druid, Troll Warlord, Legion Commander and Wraith King are some of the Heroes that base themselves on attacks with little or no spell power, so they suffer in the grassy hands of Overgrowth.

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

* Troll Warlord's high attack speed means Counter Helix will proc extremely frequently even without creeps near him. This, combined with a Blade Mail means Axe can easily solo kill Troll Warlord even in later stages of the game.
* Battle Trance does not save Troll Warlord from a Culling Blade.
Additional:
* Troll Warlord has significant attack speed due to Fervor and Battle Trance, giving Axe a higher chance to proc Counter Helix and seriously injure Troll Warlord due to his relatively low maximum health.
* Axe often purchases Blade Mail, which can help Axe turn Troll Warlord's farm and high physical damage against him. The bonus armor provided by Berserker's Call means that Troll Warlord will take a lot more damage than Axe.
* Culling Blade is still capable of killing Troll Warlord during Battle Trance if his HP is low enough.

* 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.

* Shadow Shaman's long disables are effective at kiting and wasting the duration of Battle Trance.
* Mass Serpent Ward are especially effective against Troll Warlord during Battle Trance, as trapping him inside them during the duration is effectively another hard disable, as Troll cannot attack the wards or use Phase Boots to escape.

* 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.

* 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.

* 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.

* 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.

* 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.

* Heroes who rely heavily on melee attacks and lack early spell immunity are easily blocked and interrupted by Ink Swell: Lycan, Ursa, Troll Warlord.

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

* Troll Warlord is very susceptible to Pierce the Veil due to having low health and reliance on high armor.
* Troll Warlord's ultimate Battle Trance can simply be ignored by using Pierce the Veil.
* Troll Warlord's Rampage buff for allies can easily be countered by The Calling which will lower their attack speeds back to normal.

* 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.

* Primal Roar and the slow from Boars make kiting Troll Warlord very easy.

* 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.

* Low-health, normally mobile carries who rely entirely on raw attack damage are vulnerable to Bane's nukes and disables: Anti-Mage, Clinkz, Drow Ranger, Faceless Void, Gyrocopter, Juggernaut, Meepo, Mirana, Monkey King, Morphling, Phantom Assassin, Phantom Lancer, Riki, Shadow Fiend, Slark, Sniper, Terrorblade, Troll Warlord, Weaver.

Additional:
* Nightmare and Fiend's Grip help to control/disable Troll Warlord in team-fights.

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

* Troll Warlord's high speed attack makes Retaliate deal a lot of damage to him.

* 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.

* Phantasm gives Chaos Knight a significant advantage against single-target damage dealers: Lifestealer, Wraith King, Night Stalker, Troll Warlord.

Additional:
* Chaos Knight's tanky illusions easily take advantage of Troll Warlord's lack of AoE damage.
* Chaos Bolt can stun Troll for up to 4 seconds and Reality Rift prevents Troll Warlord from chasing down foes.
* Phantasm increases Chaos Knight's physical damage output up to 4 times and can easily kill Troll Warlord before he has a chance to use Battle Trance or a Black King Bar.

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

* Heroes who cannot fight back during Arena of Blood in the early and mid game: Abaddon, Anti-Mage, Broodmother, Luna, Sniper, Troll Warlord, Weaver, Clinkz.

* Fate's Edict can disarm Troll, rendering him useless in a teamfight, especially if he has already used Battle Trance.
* Fortune's End and Purifying Flames can provide ample magic damage to help burst down Troll Warlord quickly in the early to mid game.
* False Promise can save an ally from Troll Warlord's initiation, forcing him to switch targets and lose his Fervor stacks, or waste time during Battle Trance.

* 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.

* 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.

* 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.

* 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.

* Dark Willow's burst damage and stun prevents Troll Warlord from approaching her until he has Black King Bar.
* Troll Warlord's lack of burst damage makes it hard for him to kill Dark Willow before she slips into Shadow Realm.

* 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.

* Static Link is effective against Troll Warlord, as he mainly relies on attack speed more so than damage.
* Static Link is even more effective if Troll Warlord used Battle Trance, as he has no way to break the link.
Additional:
* Static Link can drain most or all of Troll Warlord's damage, making him useless in a teamfight or unable to last hit in lane. This is especially effective during Battle Trance, because Troll has no option to cancel the link.
* Storm Surge allows Razor to chase after or run away from Troll Warlord while doing damage with Eye of the Storm.

* 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

* Timber Chain can kite Troll Warlord extremely effectively.
* Whirling Death and Chakram deals lots of damage to Troll Warlord.
* Reactive Armor makes Timbersaw extremely resilient to Troll's attack damage and extreme attack speed, especially during Battle Trance.

* 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.

* 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.

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

* Melee heroes who may struggle to get close to Sniper: Wraith King, Kunkka, Doom, Tidehunter, Underlord, Troll Warlord, and etc.

Additional:
* Shrapnel and Headshot allows Sniper to kite Troll Warlord effectively.
* Take Aim together with certain items such as Hurricane Pike allow Sniper to sit and fire at Troll Warlord from a safe distance.

* 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.

* 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.

* 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.

* 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.

* 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 strongly on melee physical damage will fare badly against Omniknight's Guardian Angel: Phantom Assassin, Juggernaut, Dragon Knight, Lycan, Ursa, Troll Warlord

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

* 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 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 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 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.

* 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.

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

Additional:
* Outworld Destroyer's pure damage from Arcane Orb is very effective at killing Troll Warlord quickly.
* Astral Imprisonment removes Troll Warlord from a fight for four seconds, minimizing his contribution to a teamfight, and potentially wasting over half of Battle Trance's duration.
* Troll Warlord gains a measly 1 intelligence point per level, meaning Sanity's Eclipse is especially effective, often instantly killing him.

* 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 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 high physical damage output but lack of reliable escape mechanisms are always a good target for a solo gank: Sniper, Shadow Fiend, Troll Warlord, Drow Ranger. Those heroes, however, are dangerous if they manage to close the gap, so take caution.

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

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

* 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.

* Other heroes that rely on physical attacks to deal damage and not their abilities: Troll Warlord, Sniper, Monkey King, Sven.

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

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

* 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 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 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 mediocre health pools who rely on armor or evasion to survive fights such as Troll Warlord, Windranger, and Terrorblade can be killed by Zeus if caught off guard.

* 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 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 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 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.

* Frostbite can disarm and root Troll Warlord if he doesn't have a Black King Bar or a Manta Style to dispel it.
* Crystal Nova and Freezing Field both significantly slow Troll Warlord, making him much more vulnerable to ganks or stuns.
* The magical damage from Freezing Field does a large amount of AoE damage, and Troll Warlord is not capable of cancelling Crystal Maiden's channel.

* 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.

* 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.

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

* 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.

* 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.

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

* Phantom Strike allows Phantom Assassin jump directly to Io.
* Coup de Grace can make a short work of Io's low health and armor.

* 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.

* Atrophy Aura decreases Troll Warlord's damage.
* Pit of Malice helps lock down Troll Warlord.
* Battle Trance disallows Troll from running out of both Firestorm and Pit of Malice.