* Cold feet can be used to ensure that the full channel of Freezing Field doesn't go off.

* 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.

* Ice Path allows Jakiro to easily cancel Freezing Field.
* Freezing Field makes Crystal Maiden an easy target for all of his abilities without a Black King Bar.
* With the Aghanim's Scepter upgraded Macropyre, Black King Bar becomes nearly useless for Crystal Maiden, as its high pure damage over time, long duration and ability to pierce spell immunity will either force Crystal Maiden to forcefully cancel Freezing Field or even discourage her from using it at all.
Additional:
* Ice Path allows Jakiro to easily cancel Freezing Field.
* Freezing Field makes Crystal Maiden an easy target for all of Jakiro's abilities without a Black King Bar.
* Aghanim's Scepter upgraded Macropyre can deal pure damage-over-time and pierce spell immunity, making Black King Bar nearly useless for Crystal Maiden, as its high damage over time and long duration can discourage Crystal Maiden to use Freezing Field. Remember, however, that Crystal Maiden can partially solve this issue by buying Aghanim's Shard, which will allow her to simply walk out of Macropyre.

* 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.

* Lucent Beam allows Luna to easily cancel Freezing Field.
* Without Black King Bar protection, Lucent Beam and Eclipse can make a short work out of Crystal Maiden's abysmal health.
* Skilled Luna will always buy Dust of Appearance, allowing her team to have a vision on Crystal Maiden while invisible and during channeling Freezing Field.
* Even with Black King Bar, Luna can still inflict considerable damage on Crystal Maiden with her attacks, which get empowered with Moon Glaives and Lunar Blessing, also smart and skilled Luna will buy Abyssal Blade to cancel Freezing Field even through Black King Bar in case of emergency. And since Crystal Maiden rarely buys Linken's Sphere, this can be a very big problem for her.
Additional:
* Lucent Beam allows Luna to easily cancel Freezing Field.
* Without Black King Bar protection, Lucent Beam and Eclipse can make a short work out of Crystal Maiden's abysmal health.
* Skilled Luna will always buy Dust of Appearance, allowing her team to have a vision on Crystal Maiden while invisible and during channeling Freezing Field.
* Even with Black King Bar, Luna can still inflict considerable damage on Crystal Maiden with her attacks, which get empowered with Moon Glaives and Lunar Blessing, also smart and skilled Luna will buy Abyssal Blade to cancel Freezing Field even through Black King Bar in case of emergency. Forcing Crystal Maiden to buy Linken's Sphere.

* 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.

* Viscous Nasal Goo can hinder Crystal Maiden's already abysmal mobility, which allows Bristleback (or his teammates) to run her down and kill her.
* Bristleback frequently builds Blade Mail, which can quickly kill Crystal Maiden if her ultimate is used while he is under its effect.
* The passive part of Bristleback will trigger many, many times under the damage from Freezing Field, and as the stacks increase, the damage output from each successive cast (or proc) will eat away at Crystal Maiden's small HP pool.

* 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.

* Phantom's Embrace can silence Crystal Maiden and disrupt Freezing Field's channeling. Her slow movement speed and fragile nature will also make her an easy target for Stroke of Fate and Ink Swell.

* 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.

* Mirror Image can dispel Frostbite. A similar effect can be achieved with Manta Style, a core item on Naga Siren.
* Song of the Siren can stop Freezing Field regardless of any kind of invisibility as well as allow Naga Siren's team to quickly close the gap on Crystal Maiden.
* With Aghanim's Scepter, Naga Siren can get access to Reel In ability, which can allow her to pull Crystal Maiden toward herself and her team and cancel Freezing Field even through Black King Bar.
Additional:
* Mirror Image can dispel Frostbite.
* Song of the Siren can stop Freezing Field regardless of any kind of invisibility as well as allow Naga Siren's team to quickly close the gap on Crystal Maiden.
* Ensnare allows Naga Siren and her team to quickly catch up with Crystal Maiden and kill her.
* With Aghanim's Scepter, Naga Siren can get access to Reel In ability , which can allow her to pull Crystal Maiden toward herself and her team and cancel Freezing Field even through Black King Bar.

* 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.

* Grave Chill will make Crystal Maiden's bad movement speed even worse.
* Soul Assumption charges can easily be stacked up from Freezing Field, allowing Visage to nuke enemies multiple times throughout the fight.
* {U:Familiar}'s Stone Form can also be used to interrupt Freezing Field, even while Crystal Maiden is under the effects of Glimmer Cape. Crystal Maiden must purchase a Black King Bar, which is far more costly.

* 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.

* Crystal Maiden is extremely fragile and she's an easy target for him. She has no real disables that can lock Ember Spirit down, and all of her skill damage can be negated with Flame Guard. The damage from Searing Chains, Flame Guard, and Sleigh of Fist can easily take her down.

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

* Being a hero with low health and abysmal mobility, Lina can nuke her down easily.
* Since Crystal Maiden's Freezing Field is a channeled ability, Lina can use her Light Strike Array to cancel it easily.

* 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.

* Boulder Smash and Geomagnetic Grip allow Earth Spirit to easily disrupt Freezing Field, regardless of where Crystal Maiden is due to their incredible range. Earth Spirit is quite possibly the best hero for stopping long channeling abilities, and Crystal Maiden is vulnerable to him without a Black King Bar.
* All of Earth Spirit's spells allow him to easily close in on Crystal Maiden and kill her. Since she is a low health support, she generally stays behind in teamfights, but Earth Spirit can easily close the distance.
* Crystal Maiden has low movement speed and no other escape mechanism, rendering her extremely vulnerable to Earth Spirit's arsenal of long-range, damaging spells.

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

* Crystal Maiden has a very bad movement speed, so Impale is easy to land against her. Furthermore, even while trapped by Frostbite, Nyx Assassin can still cast Impale.
* Crystal Maiden has very low armor, so Vendetta is very effective.
* Nyx Assassin has two ways to stop Freezing Field, provided she doesn't get a Black King Bar. He can either pop Spiked Carapace and simply walk into the field, or he can use Impale to interrupt the field, since Crystal Maiden has to channel it.
Additional:
* Spiked Carapace easily interrupts Freezing Field.
* Frostbite's damage over time sets up an easy Spiked Carapace stun.
* Crystal Maiden is extremely fragile and dies quickly to Nyx Assassin's burst 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.

* Snowball allows Tusk to easily cancel Freezing Field from a safe distance without putting himself in any danger.
* Walrus PUNCH! is most certainly a high enough damage nuke to easily kill off Crystal Maiden.
* Ice Shards can prevent the already immobile Crystal Maiden from escaping, making her an easy kill for either Tusk or a teammate.
Additional:
* Crystal Maiden's low health and armor make her an easy target for Walrus PUNCH!
* Tusk's Snowball can protect allies and cancel Freezing Field.
* Snowball and Walrus PUNCH! can interrupt Freezing Field.

* 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.

* Doom alone can easily pick off Crystal Maiden since she is fairly fragile, even with using only basic attacks, Infernal Blade, and Scorched Earth.
* Doom prevents her from using any abilities in a fight, making her impact negligible.
* Devour allows Doom to acquire a stun, allowing him to cancel Freezing Field without having to use Doom.

* 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.

* Any hero with a low HP pool is easy for Tinker to nuke down: Crystal Maiden, Enchantress, Gyrocopter, Lion, Riki, Techies, Terrorblade, Necrophos, Invoker.

* 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.

* Juggernaut and Lifestealer have abilities (Blade Fury and Rage respectively) that prevent Crystal Maiden from using her spells on them in the early game, before Black King Bar and other magical reduction is even an issue.

Additional:
* Crystal Maiden is an ideal target for Lifestealer due to her poor mobility and low health pool. Lifestealer can usually catch up to her simply by casting Rage, as none of her abilities pierce through magic immunity. Freezing Field can potentially make her even more vulnerable to Lifestealer while under Rage as she is even more immobile while channeling it.
* Lifestealer commonly buys Abyssal Blade, which allows him to cancel Freezing Field, even if Crystal Maiden is spell immune.
* Alternatively, Aghanim's Scepter upgraded Infest combined with Abyssal Blade and with items that provide attack speed which Lifestealer commonly buys allow him to to cancel Freezing Field from within the Crystal Maiden.

* 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.

* Channeling heroes will not go well against Warlock, especially those who build Black King Bar as Warlock's ultimate ability stun goes through spell immunity. E.g.: Crystal Maiden, Witch Doctor, Enigma, 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.

* In the same vein, heroes with silences — especially with the AoE ones like Death Prophet's Silence — can also prevent Crystal Maiden from being able to impact a fight.

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

* 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.

* Berserker's Call can interrupt Freezing Field, even through Black King Bar and/or Glimmer Cape.
* Battle Hunger makes Crystal Maiden's already bad movement speed even worse.
* Axe frequently builds Blade Mail, which can quickly kill Crystal Maiden if her ultimate is used while he is under its effect.

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

* 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.

* Duel is a great initiation to target Crystal Maiden with, as it prevents her from using Freezing Field or any other abilities and allowing the enemy team to quickly kill her before she can aid her team in a fight.

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

* 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.

* 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.

* Crystal Maiden will be not able to cast her Freezing Field while being constantly stunned by Enigma's Malefice.
* Enigma's Black Hole can cancel Freezing Field's channeling regardless of her Glimmer Cape and Black King Bar.

* 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.

* 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.

* Battery Assault, Power Cogs, and Hookshot can interrupt Freezing Field, the latter two being able to go through invisibility should Crystal Maiden use Glimmer Cape.
* Rocket Flare can be used to find Crystal Maiden should she try to hide in the trees to try to safely cast Freezing Field.
* Hookshot allows Clockwerk to easily close in on Crystal Maiden and kill her.

* The slow from Torrent makes Crystal Maiden's already bad movement speed even worse.
* Kunkka has many tools to interrupt Freezing Field (most notably Torrent, Ghostship and Torrent Storm from Aghanim's Scepter), as she is an easy target while channeling it.
* It is worth noting that most of Kunkka's abilities do not pierce through spell immunity, so purchasing a Black King Bar might help Crystal Maiden in this regard.

* 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.

* Crystal Maiden's low health pool and slow movement speed make her a tempting and easy target.
* However, it may be wise to build Black King Bar first before attempting to fight her alone, as she can disable you and retaliate with Freezing Field.

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

* 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.

* Gush can make Crystal Maiden's already weak armor even weaker.
* Kraken Shell can dispel Frostbite, preventing him from getting stuck inside Freezing Field.
* Ravage is very useful for interrupting Freezing Field, even while Crystal Maiden is under the effects of Glimmer Cape. Crystal Maiden must purchase a Black King Bar, which is far more costly.

* Crystal Maiden is squishy, is heavily spell reliant, has low base Intelligence, and is naturally slow, making her an ideal target for Silencer.
* Crystal Maiden's Freezing Field has a similar cooldown to Global Silence, therefore, Freezing Field can almost always be canceled to ruin aggressive Crystal Maiden initiations.

* Smoke Screen effectively disables Crystal Maiden's channeling spell: Freezing Field.
* Due to her low health and armor throughout the game, Riki can kill her easily.

* 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.

* Crystal Nova helps on farming while applies an area slow.
* Frostbite extends Rubick's lockdown duration while providing extra damage, also serves as a farming ability.
* Freezing Field deals much greater damage thanks to Arcane Supremacy in teamfights.
* Freezing Field is a channeling ability and therefore can be stolen easily.
* Crystal Maiden has no innate ability to interrupt Freezing Field, though it may not be the case for her teammates; Yet a well-times Telekinesis lift or drop can interrupt Freezing Field.
* Consider build items that strengthens Freezing Field, such as Aghanim's Shard, Black King Bar and Aghanim's Scepter to reach its full potential.

* 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 with channeled abilities which Assassinate may cancel at long range: Witch Doctor, Crystal Maiden, Shadow Shaman, Pugna

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

* 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.

* Sacred Arrow can be used to interrupt Freezing Field from a safe distance, forcing her to cancel it to dodge or get hit.
* Crystal Maiden has very slow movement speed, making her an easy Sacred Arrow target.
* Crystal Maiden has low health and can easily be killed with an Aghanim's Scepter combo or just when hit with an arrow.
* If Frostbite has already been used, Mirana can Leap away even when slowed by Crystal Nova or Freezing Field.

* 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 little health or magic resistance are easily picked off with Oracle's magic burst, such as Skywrath Mage, Crystal Maiden, or Enchantress.

* 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, heroes with AoE or long range disables (such as Faceless Void with Chronosphere, Pudge with Meat Hook and Elder Titan with Echo Stomp) hinder Crystal Maiden, preventing her from using Freezing Field to help her team in a fight.

* Heroes with low mobility that rely on spells: Zeus, Lina, Crystal Maiden.

* Lone Druid's early game is good against slow, squishy supports since his bear is very strong early game and an Entangling Claws proc almost always guarantees a kill: Ancient Apparition, Crystal Maiden, Shadow Shaman, 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.

* Heroes with strong channeling spells like Crystal Maiden's Freezing Field, Bane's Fiend's Grip, and Enigma's Black Hole can easily be interrupted from a long range by Nether Swap, assuming they don't have a Linken's Sphere.

* 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 supports who die in a few hits against Sven's high physical damage: Crystal Maiden, Vengeful Spirit, Dark Willow.

* 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.

* Low mobility heroes: Heroes with no/little means of traveling fast have difficulty getting to/away from Bounty Hunter due to his slowing Jinada and hastening Track. Few examples of such heroes are: Crystal Maiden, Sniper, Ursa, Witch Doctor, etc.

Additional:
* Shuriken Toss's stun is useful for cancelling Freezing Field from a distance.
* Track can be used for revealing Crystal Maiden when she uses Glimmer Cape.
* Jinada does burst physical damage (which is even bigger if dealt under Track's crits), which is effective due to Crystal Maiden's low HP and armor.
* Bounty Hunter likes to stay hidden from the fight and is less likely to get caught by Crystal Maiden's spells.

* 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.

* Generally, any fragile heroes will have a hard time dealing with Undying's tankiness, and even more so if Decay is used on them. Some examples are Crystal Maiden and Witch Doctor.

* 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 channeled abilities can be interrupted by a long-range Fissure: Crystal Maiden, Witch Doctor, Bane, Pugna, Pudge.

* 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.

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

* Any hero with low mobility and max healthsuch as Silencer, Crystal Maiden etc.

* Heroes that have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include Crystal Maiden, Witch Doctor, Warlock or Shadow Fiend.

* In general, heroes with AoE or long range disables (such as Faceless Void with Chronosphere, Pudge with Meat Hook and Elder Titan with Echo Stomp) hinder Crystal Maiden, preventing her from using Freezing Field to help her team in a fight.

* 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.

* Crystal Maiden's already low armor and easily interruptible ultimate, Freezing Field can make Slardar her worst nightmare. Crystal Maiden also often builds Glimmer Cape which is revealed by Corrosive Haze.

* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: Lich, Crystal Maiden, Silencer, Keeper of the Light, Venomancer, 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.

* Long range disables are really effective against dangerous area controllers and channeling Heroes, like Enigma, Faceless Void or Crystal Maiden, as it may cancel them or prevent enemies from doing further damage while keeping Lion in a relatively safe distance in the warzone.

* Innately fragile heroes will die almost instantly to Reality Rift while Chaos Knight has illusions active: Drow Ranger, Bane, Necrophos, Crystal Maiden.

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

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

* 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.

* As Crystal Maiden is squishy with very bad movement speed, Spectre can easily stay on Crystal Maiden with Haunt and Spectral Dagger.
* Late game, with enough farm, Spectre can withstand an entire Freezing Field, possibly even causing Crystal Maiden to kill herself from Dispersion.

* Puck has both Waning Rift and Dream Coil to stop Freezing Field's channel regardless of whether or not Crystal Maiden has a Glimmer Cape, as both spells fully affect invisible units.

* 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 supports with low armor are always a good prey, also her Psionic Trap will wear down most attempts to flee with their built-in disables: Silencer, Crystal Maiden, Warlock, Ancient Apparition, Grimstroke, Witch Doctor

* 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 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 low health are especially vulnerable to Marksmanship's high damage output: Clinkz, Crystal Maiden.

* Heroes with a low attack speed or are fragile will find themselves unable to deal with Troll Warlord's high physical damage and attack speed, like Crystal Maiden or Sven.

* Heroes with slow movement speeds and small health pools (supports like Crystal Maiden or Witch Doctor) are easy targets for Phoenix. Should they be inflicted by its DOT debuffs, they will be very quickly killed without even getting a chance to fight back.

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

* Heroes who rely on channeling abilities can be interrupted in teamfights by Rolling Thunder: Crystal Maiden, Pugna, Witch Doctor

* Heroes with large health pools (Pudge) or good innate magic resistance (Anti-Mage) can be very problematic for Crystal Maiden, since even if they are under the effect of her ultimate for the entire duration, the damage output is simply not enough to kill or force them to retreat.

* Heroes with a low health pool (Crystal Maiden, Skywrath Mage etc)

* Even with Black King Bar or Linken's Sphere, Pudge's Meat Hook can still cancel Crystal Maiden's Freezing Field as she is a very easy target while channeling it.
* Pudge's Rot can make Crystal Maiden's already bad movement speed even worse.
* Many stacks of Flesh Heap will make it nearly impossible for Crystal Maiden to kill Pudge.
* Pudge's Dismember can also be used to cancel Crystal Maiden's Freezing Field, and alternatively, Pudge can also use it to save allies from getting killed by Crystal Maiden and heal them when upgraded with Aghanim's Shard.
* Crystal Maiden is prone to ganks in the lane or in the off-lane without proper vision. Pudge can take advantage of Crystal Maiden's lack of mobility, and gank her often.
Additional:
* Meat Hook can cancel Freezing Field, even if Crystal Maiden has Glimmer Cape.
* She is also slow and fragile, making her a good target for ganking.

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

* Juggernaut and Lifestealer have abilities (Blade Fury and Rage respectively) that prevent Crystal Maiden from using her spells on them in the early game, before Black King Bar and other magical reduction is even an issue.