* Storm's Dispel Magic combined with Thunder Clap deals high damage against Chaos Knight's illusions even in the late game.
* Chaos Knight's reliance on physical damage is easily hindered by Drunken Brawler.
* Chaos Knight's lack of area effect and mobility makes him easily overwhelmed by Primal Split.
Additional:
* Dispel Magic from {U:Storm} can instantly kill the Phantasm army early on, and can still deal a lot of damage to them late game, revealing the real Chaos Knight.

* Primal Split makes Brewmaster invulnerable for the duration, rendering effects of Cold Feet and Ice Blast useless.
* Dispel Magic can dispel Cold Feet from allies.
* Brewmaster can easily run Ancient Apparition down with the slow from Thunder Clap and Cinder Brew.

* Anti-Mage easily Blinks out of Cold Feet's freeze radius.
* Ancient Apparition lacks mobility, thus making him fall easily to Mana Void.
Additional:
* Anti-Mage can Blink away from Cold Feet or build a Manta Style to dispel it.
* Counterspell minimizes the damage Anti-Mage takes from all of Ancient Apparition's abilities.
* Mana Break and Mana Void deal a lot of damage to Ancient Apparition due to his high mana pool.

* Anti-Mage commonly builds Battle Fury, which can deal with Phantasm illusions easily.
* Counterspell, if timed right, will turn Chaos Bolt against the Knight, and can set up for a kill if he is not careful.
* Even if Counterspell is on cooldown, Blink can almost always dodge a Chaos Bolt because of its slow projectile.
* Mana Break will quickly drain Chaos Knight's mana.

* Phantom Lancer can dispel or escape from Cold Feet with Doppelganger and Phantom Rush, respectively. Phantom Lancer also frequently builds a Manta Style which dispels Cold Feet.
* Ancient Apparition has trouble dealing with Phantom Lancer's illusions due to a lack of Area of Effect damage other than Ice Blast.
* Phantom Lancer tends to build a Diffusal Blade, which greatly amplifies his damage against Ancient Apparition due to Ancient Apparition's high mana pool.
* Ancient Apparition has no escape/mobility mechanisms, making him an easy target for Phantom Lancer at any stage of the game.

* Chaos Knight's single target abilities are difficult to target against Phantom Lancer's illusions.
* Chaos Knight's lack of mobility makes him an easy target for Phantom Lancer to Phantom Rush and drain his already low mana pool.
Additional:
* Juxtapose allows Phantom Lancer to overwhelm Chaos Knight due to his single-target abilities.
* Doppelganger can be used to dodge Chaos Bolt.
* Spirit Lance can be used to harass Chaos Knight during the early game.
* Since Phantom Lancer builds Diffusal Blade often, it can quickly drain Chaos Knight of all his mana, leaving him unable to cast spells.

* Heroes with mobility/escape mechanisms to dodge Ancient Apparition abilites, or to easily jump on him: Riki, Queen of Pain, Phantom Assassin, Windranger, Bounty Hunter, Spirit Breaker, Night Stalker, Storm Spirit, Juggernaut, etc.

* As long as Windranger is able to identify the real hero among the illusions, heroes relying on them can be easily tagged with Focus Fire: Chaos Knight, Terrorblade, Phantom Lancer, Naga Siren.

* Finger of Death can instantly shred many targets especially fragile Heroes like Keeper of the Light, Ancient Apparition, or Bounty Hunter.

* One of Lion's level 20 talents lets Mana Drain affect 2 secondary targets. This can make things difficult for heroes like Phantom Lancer, Chaos Knight, and Terrorblade who rely on illusion armies.
* Mana Drain and Hex instantly kill any illusions. Finger of Death upgraded with Aghanim's Scepter also shreds most illusions.
* One of Lion's level 20 talents lets Mana Drain affect 2 secondary targets. This can make things difficult for heroes like Phantom Lancer, Chaos Knight, and Terrorblade who rely on illusion armies.

Additional:
* Mana Drain is a real problem to Chaos Knight in the early game, considering his already low mana pool.
* Aghanim's Scepter upgraded Finger of Death is an AoE ability, which can deal a tremendous amount of damage to his illusions.
* Lion has two abilities that can instantly kill illusions. Provided that he does not get stunned by Chaos Bolt first, Lion can render Phantasm near-useless.

* Squishy heroes, usually supports, like Io, Ancient Apparition, Keeper of the Light etc can die instantly from Tiny's magic burst.

* Melee carries will have a hard time against Tiny's Craggy Exterior: Phantom Assassin, Chaos Knight, Juggernaut.

* The area of effect damage from Midnight Pulse and Black Hole help deal with Chaos Knight's illusions.
Additional:
* Black Hole usually catches Chaos Knight with all his illusions.
* Midnight Pulse deals damage based on max health, quickly killing Phantasm illusions.

* Shapeshift increases Lycan's movement speed and renders him unslowable, allowing him to easily avoid and escape Ancient Apparition's abilities.
* Lycan has many fast summons, both his wolves from Summon Wolves and from the frequently built Necronomicon, all of which can do heavy damage to Ancient Apparition due to his immobility and low armor.

* Decrepify turns the target ethereal, protecting them from Chaos Knight's and his illusions' attacks.
* Life Drain instantly destroys illusions. It can effectively negate Phantasm when upgraded with Aghanim's Scepter.
* Nether Blast quickly clears out illusions and can harass Chaos Knight in lane.

* Puck's area of effect nukes in the form of Illusory Orb and Waning Rift clears Phantasm illusions from the early game to mid game.
* Phase Shift can be used to disjoint Chaos Bolt.

* Leap allows Mirana to easily escape the freezing range of Cold Feet. Mirana also tends to build Manta Style which dispels Cold Feet.
* During Moonlight Shadow, the invisibility makes it hard to catch Mirana's team with Ice Blast.
* Ancient Apparition's lack of mobility/escape capabilities makes him an easy target for Mirana at any stage of the game.

* Cold Feet is extremely easy to nullify with Shukuchi.
* Ice Vortex does not slow Weaver in Shukuchi.
* Time Lapse will still affect his health, even when hit by Ice Blast.
* Ancient Apparition has no escapes or saves and is very squishy, making him an easy target for Weaver to get on top of.
Additional:
* Time Lapse allows Weaver (or an ally if upgraded with Aghanim's Scepter) to regain HP while affected by Ice Blast.
* Shukuchi completely ignores the slow from Ice Vortex and helps him escape the freeze range of Cold Feet.

* False Promise can prevent the shatter from Ice Blast and Fate's Edict can protect an ally from the magical damage over time for a while.
* Oracle can deny allies who are frostbitten. If he uses Purifying Flames to reach the shatter threshold, it will count as a deny.
* Fortune's End can dispel Cold Feet on affected allies, preventing them from getting frozen.
Additional:
* False Promise can dispel the stun from Cold Feet and can save an ally that's about to shatter from Ice Blast, even allowing healing with Purifying Flames by delaying it until after the debuff expires.
* Purifying Flames allows Oracle to deny his allies if they're affected by Ice Blast. If he brings his allies' health to or below the shatter threshold, it will count as him denying the ally. However, this does not work on Oracle himself.
* Fate's Edict provides 100% magic resistance, making it good against all of Ancient Apparition's abilities at all stages of the game.
* Fortune's End can dispel Cold Feet from allies.

* With his AoE damage, Jakiro can easily kill Chaos Knight's Phantasm illusions.
* Chaos Knight usually doesn't buy a Black King Bar, making him vulnerable to an Ice Path into Macropyre combination.
Additional:
* Ice Path and Macropyre punish Reality Rift with a long stun and heavy damage across all illusions.

* Flak Cannon destroys Chaos Knight's illusions very quickly.

* Wukong's Command and Boundless Strike combo can easily cause havoc on Chaos Knight by destroying all of his powerful illusions.
* Chaos Knight without Phantasm cannot deal with Jingu Mastery at all.

* Ravage damages and disables Chaos Knight's army.
* Anchor Smash deals respectable area damage at early levels and lowers Chaos Knight's damage.
* Kraken Shell dispels Chaos Bolt and Reality Rift while providing protection from damage.

* Dissimilate and Astral Step allow Void Spirit to quickly escape from Cold Feet.
* Void Spirit deals both magical and physical damage, which makes Ancient Apparition an easy target to ambush.
* If Void Spirit purchases Aghanim's Scepter, the silence provided by Resonant Pulse can disrupt Ancient Apparition during fights, as he is entirely reliant upon spells to contribute.

* Supernova with or without Aghanim's Scepter allows to save ally or himself through Ice Blast.
* Icarus Dive quickly escapes from Cold Feet.
Additional:
* Icarus Dive helps Phoenix escape from Cold Feet.
* However, all of Pheonix's basic abilities do cost health, which can be harmful under the effects of Ice Blast
* Supernova can save Phoenix from Ice Blast.

* Illusion-based heroes such as Naga Siren or Chaos Knight are vulnerable to Phoenix's DPS and attack speed slow, as their illusions, no matter how many, will be unable to deal enough damage to actually be a threat, and they will all be completely useless against the Supernova.

* Ancient Apparition's only skill to stop Storm Spirit is Cold Feet, which is bad in general when trying to stop a Storm Spirit without any other disable.
* As a fragile support with low Strength gain and no magic resistance, Ancient Apparition is vulnerable to Storm Spirit's combos.

* Echo Slam's damage potential increases due to Chaos Knight's Phantasm illusions.
Additional:
* Echo Slam will deal a colossal amount of damage to your army, as will Fissure at lower levels.
* The area stuns from Aftershock will always slow down your illusions, since they can't have spell immunity.

* Chain Frost can eliminate Chaos Knight's Phantasm army, especially after he clumped up using Reality Rift.
* Frost Shield will heavily reduce his army's effectiveness.
Additional:
* Lich's Chain Frost, especially after obtaining its respective talent that provides unlimited bounces, can take out all of Chaos Knight's illusions quickly.
* An Aghanim's Scepter-upgraded Sinister Gaze can hypnotize Chaos Knight and his illusions while also draining his already low mana pool.

* Berserker's Call and Counter Helix makes short work of Chaos Knight's Phantasms.
Additional:
* Berserker's Call allows Axe to lock down Chaos Knight and his illusions.
* Counter Helix combined with Blade Mail clears illusions out in no time.

* As Ancient Apparition likes to stay far away from the fight to get full effectiveness from Ice Blast, he is a very good target for a Haunt gank.
* Ancient Apparition also has no hard disables and escape spells, making him an easy kill for Spectre.

* Ember Spirit is evasive and can dodge close encounters with melee heroes like Chaos Knight. Ember Spirit can't be caught with the slow from Reality Rift, and Flame Guard and Sleight of Fist can bring Phantasm's illusions down quickly.

* Sunder is not affected by Ice Blast and will still swap health with any target as usual.
Additional:
* Sunder allows Terrorblade (or an ally) to regain HP while affected by Ice Blast.
* Terrorblade often buys Manta Style which can dispel Cold Feet

* Lina builds Shadow Blade (and upgrades it into a Silver Edge), which makes it hard for Ancient Apparition to land his abilities.
* Laguna Blade can kill Ancient Apparition easily due to his low health pool and lack of mobility.

* Using Reality Rift sets up a Reverse Polarity on Chaos Knight and his illusions.
* Shockwave and Skewer kill Phantasm's illusions quickly, as can Empower cast on a melee carry.
Additional:
* All Magnus abilities are very good against Chaos Knight's Phantasm illusions.

* Tidebringer, Torrent and Ghostship destroys Chaos Knight's Phantasm army all through the game.

* Great Cleave is very effective against Chaos Knight's illusions.
* Storm Hammer's radius can catch all of Chaos Knight's illusions at once, especially after Reality Rift.
* Warcry shields Sven and his teammates against Chaos Knight's burst physical damage.
Additional:
* Storm Hammer's faster projectile speed and cast time allows Sven to stun Chaos Knight and his illusions before he can cast Chaos Bolt.
* Warcry's armor bonus counteracts Reality Rift's debuff and reduces Chaos Knight's damage output.
* Great Cleave and God's Strength devastates Phantasm illusions.

* Heroes with silence and mana drain abilites, as Ancient Apparition relies entirely on his abilities: Invoker, Silencer, Nyx Assassin, Skywrath Mage, Shadow Shaman, Lion and etc.

* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: Naga Siren, Phantom Lancer, Broodmother

* Ancient Apparition has no escape or reliable control and is very fragile, which makes him an easy target for anyone who can get on top of him, like Phantom Assassin or Clinkz.

* Heroes that rely on illusions will suffer against Ion Shell, which kills them very quickly: Phantom Lancer, Chaos Knight, Naga Siren, Meepo.
* Heroes that rely on illusions typically spawn very strong illusions inside your Wall of Replica that you should use against them or their team.

* Illusion based heroes (like Chaos Knight and Terrorblade) can't use their illusion beneficially against Sanity's Eclipse's high AoE burst damage.

* Because of his massive AoE damage, Sand King is very effective against illusion heroes: Chaos Knight, Phantom Lancer, Terrorblade,...

Additional:
* Sand King's massive area damage output, particularly Epicenter, allows him to quickly take down Chaos Knight and his illusions.
* He can apply Caustic Finale to illusions with attacks for extra damage.

* Heroes with mobility/escape mechanisms to dodge Ancient Apparition abilites, or to easily jump on him: Riki, Queen of Pain, Phantom Assassin, Windranger, Bounty Hunter, Spirit Breaker, Night Stalker, Storm Spirit, Juggernaut, etc.

* Heroes with silence and mana drain abilites, as Ancient Apparition relies entirely on his abilities: Invoker, Silencer, Nyx Assassin, Skywrath Mage, Shadow Shaman, Lion and etc.

* Heroes who are illusion based, or even heroes who frequently build Manta Style can be cleared quickly by Pangolier's high damage, or lose their damage ouput because of Lucky Shot: Chaos Knight, Naga Siren

* Heroes who are reliant on illusions: Chaos Knight, Phantom Lancer, Naga Siren.

* Heroes with mobility/escape mechanisms to dodge Ancient Apparition abilites, or to easily jump on him: Riki, Queen of Pain, Phantom Assassin, Windranger, Bounty Hunter, Spirit Breaker, Night Stalker, Storm Spirit, Juggernaut, etc.

* Heroes who are reliant on illusions or summons: Chaos Knight, Broodmother, Naga Siren.

* For the same reason, he has to be slightly more cunning when playing against heroes that can scout the treeline, such as Ancient Apparition and his Ice Vortex and Shadow Demon and his Shadow Poison.

* Heroes with mobility/escape mechanisms to dodge Ancient Apparition abilites, or to easily jump on him: Riki, Queen of Pain, Phantom Assassin, Windranger, Bounty Hunter, Spirit Breaker, Night Stalker, Storm Spirit, Juggernaut, etc.

* With Aghanim's Scepter, Tinker's Laser completely stops Chaos Knight's damage, forcing him to buy either a Black King Bar for his own survivability while leaving his illusions still vulnerable, or a Monkey King Bar leaving him still vulnerable to Tinker's nukes, though improving his damage.
* Tinker rarely finds himself in the middle of a fight, which is where Chaos Knight typically thrives, and even in the rare cases of being so, at level 3 Tinker's constant rearm and blink away can kite and dodge Chaos Knight's spells reliably, so Chaos Knight has very little catch against Tinker's mobility. This gives Tinker impunity to create more chaos in a teamfight than Chaos Knight can control, laying down the field with March of the Machines and constantly being hit by rockets and lasers.
Additional:
* Tinker's Aghanim's Scepter upgraded Laser can blind him and all of his Phantasm illusions.

* Reactive Armor helps Timbersaw to endure the damage from Chaos Bolt and Reality Rift combo.
* Timbersaw's large amount of pure damage AoE nukes clears Chaos Knight's illusions quickly, drastically reducing his damage.
Additional:
* Strong area damage, particularly from Whirling Death and Chakram, lets Timbersaw clear out illusions quickly.
* Whirling Death directly reduces Strength from both Chaos Knight and his Phantasm illusions, reducing both the damage output and raw health that the hero relies on.
* Reactive Armor quickly builds stacks against Phantasm illusions, making Timbersaw hard to kill.
* Timber Chain allows Timbersaw to escape while surrounded.

* Phantasms can be easily killed with Purification.
* Heavenly Grace dispels the stun from Chaos Bolt and the armor reduction from Reality Rift.
* Guardian Angel works well against Chaos Knight's overwhelming reliance on physical burst damage.
Additional:
* Purification heals a teammate targeted by Reality Rift and heavily damages Chaos Knight and his illusions in the process.
* Guardian Angel blocks all of Chaos Knight's damage for a duration.

* Maledict cannot be dispelled by Phantasm, and can be used to tag the real Chaos Knight hiding within his illusions.
* If Witch Doctor has an Aghanim's Scepter, Death Ward will bounce between Chaos Knight's illusions, destroying them quickly.
* However, Death Ward is easily interrupted by Chaos Bolt until Witch Doctor buys Glimmer Cape or Black King Bar.

* Quill Spray quickly destroys Chaos Knight's Phantasms.