Puck
[wiki] rating: 1.6 (winrate: 52% pickrate: 14%)Lion
[wiki] rating: 1.2 (winrate: 49% pickrate: 15%)Keeper of the Light
* Mana Drain is very effective against heroes that have mana burn abilities such as 
Anti-Mage, 
Nyx Assassin and 
Keeper of the Light.
Chaos Knight
* 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 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.
Meepo
[wiki] rating: 1.2 (winrate: 47% pickrate: 1%)Chaos Knight
* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: 
Naga Siren, Phantom Lancer, 
Meepo, 
Broodmother
Keeper of the Light
* Heroes that can jump and kill him: Meepo, 
Clinkz, 
Templar Assassin
Tiny
[wiki] rating: 1.2 (winrate: 45% pickrate: 7%)Chaos Knight
* Melee carries will have a hard time against Tiny's Craggy Exterior: 
Phantom Assassin, Chaos Knight, 
Juggernaut.
Keeper of the Light
* Squishy heroes, usually supports, like 
Io, 
Ancient Apparition, Keeper of the Light etc can die instantly from Tiny's magic burst.
Nyx Assassin
[wiki] rating: 1.0 (winrate: 55% pickrate: 11%)Keeper of the Light
* 
Mana Burn is strong against Keeper of the Light due to his high mana pool.
* 
Spiked Carapace can be used to reflect Illuminate damage and stun Keeper of the Light.
* 
Vendetta allows Nyx Assassin to follow Keeper of the Light around if he tries to split-push.
Abaddon
[wiki] rating: 1.0 (winrate: 53% pickrate: 3%)Chaos Knight
* Abaddon could punish Chaos Knight for using Phantasm and Reality Rift combo on him with his 
Aphotic Shield. Additionally, it provides extra protection against Chaos Knight's potential to take Abaddon down quickly.
* Furthermore, Abaddon's 
Borrowed Time makes it utterly impossible to burst Abaddon down.
Tidehunter
[wiki] rating: 1.0 (winrate: 52% pickrate: 7%)Chaos Knight
* 
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.
Winter Wyvern
[wiki] rating: 1.0 (winrate: 51% pickrate: 5%)Chaos Knight
* 
Cold Embrace protects targets of Reality Rift.
* 
Winter's Curse turns Phantasm illusions against Chaos Knight or a teammate.
* 
Splinter Blast deals decent area damage to Phantasm illusions.
* 
Arctic Burn's percentage-based damage quickly wears down Chaos Knight's health.
Additional:
* Winter Wyvern can make Chaos Knight's illusions attack the real one, provided the player knows who it is.
* Alternatively, Winter's Curse can make Chaos Knight and all his illusions attack one of his allies.
* Cold Embrace protects ally who is focused by Chaos Knight.
* Splinter Blast deals decent area damage to Chaos Knight's illusions.
Pugna
[wiki] rating: 1.0 (winrate: 51% pickrate: 4%)Chaos Knight
* 
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.
Timbersaw
[wiki] rating: 1.0 (winrate: 50% pickrate: 7%)Chaos Knight
* 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.
Omniknight
[wiki] rating: 1.0 (winrate: 50% pickrate: 3%)Chaos Knight
* 
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.
Dragon Knight
[wiki] rating: 1.0 (winrate: 50% pickrate: 2%)Chaos Knight
* 
Dragon Blood's armor bonus greatly reduces the damage dealt by Phantasm.
* 
Breathe Fire and 
Elder Dragon Form's splash damage quickly destroy illusions and reduces their damage output.
Jakiro
[wiki] rating: 1.0 (winrate: 49% pickrate: 11%)Chaos Knight
* 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.
Brewmaster
[wiki] rating: 1.0 (winrate: 49% pickrate: 2%)Chaos Knight
* 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 game and can still deal a lot of damage to them late game, revealing the real Chaos Knight.
Axe
[wiki] rating: 1.0 (winrate: 49% pickrate: 10%)Chaos Knight
* 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.
Legion Commander
[wiki] rating: 1.0 (winrate: 49% pickrate: 13%)Chaos Knight
* Heroes who rely on illusions will see them destroyed easily by Overwhelming Odds: Phantom Lancer, Chaos Knight, Terrorblade, Naga Siren
Keeper of the Light
* 
Press the Attack can dispel the blind from Blinding Light from a hero.
* 
Duel can be used to instantly take Keeper of the Light out of a team-fight.
Keeper of the Light
* Heroes with abilities that blind or cause Legion Commander to miss will prevent her from winning Duels: 
Arc Warden, Keeper of the Light, 
Riki
Lich
[wiki] rating: 1.0 (winrate: 49% pickrate: 12%)Chaos Knight
* 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.
Phantom Lancer
[wiki] rating: 1.0 (winrate: 49% pickrate: 7%)Chaos Knight
* 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 rush and drain of mana.
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 build 
Diffusal Blade often, it can quickly drain Chaos Knight of all his mana, leaving him unable to cast spells.
Earthshaker
[wiki] rating: 1.0 (winrate: 49% pickrate: 10%)Chaos Knight
* 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.
Gyrocopter
[wiki] rating: 1.0 (winrate: 48% pickrate: 3%)Chaos Knight
* Flak Cannon destroys Chaos Knight's illusions very quickly.
Witch Doctor
[wiki] rating: 1.0 (winrate: 47% pickrate: 12%)Chaos Knight
* 
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.
Ember Spirit
[wiki] rating: 1.0 (winrate: 47% pickrate: 9%)Chaos Knight
* 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.
Kunkka
[wiki] rating: 1.0 (winrate: 46% pickrate: 4%)Chaos Knight
* Tidebringer, Torrent and Ghostship destroys Chaos Knight's Phantasm army all through the game.
Bristleback
[wiki] rating: 1.0 (winrate: 45% pickrate: 7%)Chaos Knight
* Quill Spray quickly destroys Chaos Knight's Phantasms.
Broodmother
[wiki] rating: 0.6 (winrate: 56% pickrate: 2%)Chaos Knight
* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: Naga Siren, Phantom Lancer, Meepo, Broodmother
Clinkz
[wiki] rating: 0.6 (winrate: 53% pickrate: 6%)Keeper of the Light
* Heroes that can jump and kill him: Meepo, Clinkz, Templar Assassin
Sand King
[wiki] rating: 0.6 (winrate: 52% pickrate: 10%)Chaos Knight
* 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.
Dark Seer
[wiki] rating: 0.6 (winrate: 51% pickrate: 3%)Chaos Knight
* 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.
Naga Siren
[wiki] rating: 0.6 (winrate: 51% pickrate: 2%)Chaos Knight
* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: Naga Siren, Phantom Lancer, Meepo, Broodmother
Phoenix
[wiki] rating: 0.6 (winrate: 51% pickrate: 10%)Chaos Knight
* 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.
Oracle
[wiki] rating: 0.6 (winrate: 50% pickrate: 9%)Keeper of the Light
* Heroes with dispels: 
Legion Commander, 
Oracle, 
Slark
Storm Spirit
[wiki] rating: 0.6 (winrate: 50% pickrate: 10%)Keeper of the Light
* Heroes with teleports to escape Will-O-Wisp: Phantom Assassin, 
Puck, 
Queen of Pain, 
Storm Spirit
Windranger
[wiki] rating: 0.6 (winrate: 49% pickrate: 16%)Chaos Knight
* Heroes who rely on illusions can be tagged by Focus Fire: Chaos Knight, Terrorblade.
Centaur Warrunner
[wiki] rating: 0.6 (winrate: 49% pickrate: 4%)Chaos Knight
* Heroes who are reliant on illusions: Chaos Knight, Phantom Lancer, Naga Siren.
Queen of Pain
[wiki] rating: 0.6 (winrate: 48% pickrate: 9%)Keeper of the Light
* Heroes with teleports to escape Will-O-Wisp: Phantom Assassin, Puck, Queen of Pain, Storm Spirit
Grimstroke
[wiki] rating: 0.6 (winrate: 47% pickrate: 8%)Chaos Knight
* Heroes who are reliant on illusions or summons: Chaos Knight, Broodmother, Naga Siren.
Snapfire
[wiki] rating: 0.6 (winrate: 46% pickrate: 10%)Chaos Knight
* Heroes reliant on illusions or summons: Broodmother, Chaos Knight, Naga Siren.
Outworld Destroyer
[wiki] rating: 0.6 (winrate: 45% pickrate: 2%)Chaos Knight
* Illusion based heroes (like Chaos Knight and Terrorblade) can't use their illusion beneficially against Sanity's Eclipse's high AoE burst damage.
Tinker
[wiki] rating: 0.4 (winrate: 49% pickrate: 8%)Chaos Knight
* 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.
Chaos Knight
* Illusion heroes, such as Naga Siren, Phantom Lancer, Chaos Knight, Terrorblade will become strong against Tinker in the late game when Tinker's only area of effect damage, March of the Machines, ceases to kill illusions quickly. Without Aghanim's Scepter Tinker is forced to defensively disarm heroes with Laser, leaving illusions free to deal physical damage which Tinker's low armor makes highly effective. In addition, 
Mjollnir or 
Battle Fury, two common pickups against illusion heroes, don't work well on Tinker at all.
Magnus
[wiki] rating: 0.4 (winrate: 46% pickrate: 7%)Chaos Knight
* 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.
Keeper of the Light
* Any hero who can counter-initiate in anticipation without getting caught in Reverse Polarity: 
Sven, 
Omniknight, 
Enigma, 
Luna, Naga Siren, 
Mars, 
Jakiro, 
Venomancer, 
Elder Titan, 
Faceless Void, 
Rubick, Keeper of the Light, 
Pugna, 
Invoker, 
Spectre, 
Alchemist, 
Treant Protector, 
Lina, Oracle, 
Zeus, 
Shadow Shaman, 
Phoenix, 
Razor, 
Huskar, 
Batrider, 
Kunkka, 
Tidehunter, 
Wraith King, 
Sand King.
Sven
[wiki] rating: 0.4 (winrate: 42% pickrate: 2%)Chaos Knight
* 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:
* Sven's shorter cast time allows him to use 
Storm Hammer on Chaos Knight and his illusions before he can cast Chaos Bolt.
* 
Warcry's armor bonus counteracts Reality Rift's slow and reduces Chaos Knight's damage output.
* 
Great Cleave and 
God's Strength devastates Phantasm illusions.
Keeper of the Light
* Keeper of the Light's AoE blind can keep Sven from landing hits.
Wraith King
[wiki] rating: -2.0 (winrate: 53% pickrate: 21%)Chaos Knight
* Wraith King has no form of AoE to clear Chaos Knight's illusions from Phantasm.
* Wraith King is very vulnerable if he reincarnates in the middle of his illusions.
Keeper of the Light
* Wraith King's poor mobility makes him vulnerable to Illuminate.
* Blinding Light can reduce his damage output as well as his already abysmal mobility.
* Chakra Magic drains Wraith King's much-needed mana resulting in him not being able to reincarnate
Techies
[wiki] rating: -1.6 (winrate: 48% pickrate: 6%)Keeper of the Light
* Heroes with flying vision such as 
Visage, 
Beastmaster, Keeper of the Light, or 
Night Stalker can scout your mines from outside their trigger radius.
Chaos Knight
* Phantasm's illusions can be used to push towers and force Techies to detonate 
Remote Mines.
* Phantasm's illusions can be used to sweep 
Proximity Mines and 
Stasis Traps.
* Chaos Knight can easily kill a lone Techies before they 
Blast Off!.
Beastmaster
[wiki] rating: -1.6 (winrate: 55% pickrate: 4%)Chaos Knight
* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: 
Bane, Beastmaster, 
Bloodseeker, 
Clockwerk, 
Doom, Shadow Shaman.
Keeper of the Light
* 
Illuminate clears Beastmaster's summons and is effective against his push.
Medusa
[wiki] rating: -1.0 (winrate: 46% pickrate: 2%)Keeper of the Light
* 
Chakra Magic can drain her current mana, draining away her effective health in a sneaky way.
* 
Will-O-Wisp will keep Medusa busy after she got hit by 
Blinding Light.
Rubick
[wiki] rating: -1.0 (winrate: 47% pickrate: 17%)Chaos Knight
* While Chaos Knight can land far away from Rubick due to 
Telekinesis, it can be counteracted by Reality Rift.
* Phantasm dispels 
Fade Bolt's damage reduction debuff.
* Rubick is fragile and can easily be killed by Chaos Knight and Phantasm's illusions, before he retaliates.
Pudge
[wiki] rating: -1.0 (winrate: 47% pickrate: 22%)Chaos Knight
* Phantasm's illusions make it difficult to land 
Meat Hook and 
Dismember.
* Chaos Bolt is a comparatively low cooldown tool to interrupt Dismember.
* Chaos Strike's lifesteal offsets 
Rot's damage.
Viper
[wiki] rating: -1.0 (winrate: 48% pickrate: 7%)Chaos Knight
* Viper has no response to the standard initiation combo of Reality Rift into Chaos Bolt.
* Phantasm can eliminate Viper almost instantly with its damage output.
Additional:
* As Viper focuses on single-target damage, he has trouble fighting off Phantasm illusions.
* Reality Rift counteracts Viper's slows and reduces his durability.
Slark
[wiki] rating: -1.0 (winrate: 48% pickrate: 12%)Keeper of the Light
* Heroes with dispels: Legion Commander, Oracle, Slark
Chaos Knight
* 
Dark Pact is minimally effective against Phantasm illusions, and Slark lacks area damage otherwise.
* 
Pounce can be counteracted by Reality Rift.
* Slark is naturally frail and dies quickly to Chaos Knight's burst damage before he can build 
Essence Shift stacks.
* Be aware, however, that 
Shadow Dance can make Slark hard to kill as he can't be targeted during its duration.
Additional:
* Phantasms have enough health to survive Dark Pact, and Slark has no other source of AoE damage to deal with them.
Keeper of the Light
* Melee carries during the laning phase: Sven, Slark
Zeus
[wiki] rating: -1.0 (winrate: 49% pickrate: 11%)Chaos Knight
* Chaos Knight's high health pool makes him resistant to Zeus' burst damage. Phantasm can dispel 
Veil of Discord, a typical item purchased by Zeus.
* Zeus is easily overwhelmed by Chaos Knight's strong illusions, as Arc Lightning is not enough to kill them fast enough to have any impact.
* Zeus' low base armor makes him extremely vulnerable to Chaos Knight's high damage output and armor reduction.
Silencer
[wiki] rating: -1.0 (winrate: 49% pickrate: 8%)Chaos Knight
* Casting Phantasm before a fight minimizes the disruption from 
Global Silence.
* Because Chaos Knight generally relies on attack damage, Silencer's spells won't be as effective against him.
Drow Ranger
[wiki] rating: -1.0 (winrate: 50% pickrate: 8%)Chaos Knight
* Reality Rift will disable Drow Ranger's Marksmanship, along with Chaos Bolt he can keep her locked for enough time to be killed.
* Phantasm's illusions are hard for Drow Ranger to deal with as she lacks of AoE damage.
Troll Warlord
[wiki] rating: -1.0 (winrate: 50% pickrate: 9%)Chaos Knight
* 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.
Arc Warden
[wiki] rating: -1.0 (winrate: 51% pickrate: 5%)Chaos Knight
* Chaos Knight can dispel Flux with Phantasm.
* Chaos Knight can use Reality Rift to pull Arc Warden out of Magnetic Field.
* Once Chaos Knight jumps on Arc Warden with Reality Rift, Arc Warden struggles to escape due to low mobility.
Lone Druid
[wiki] rating: -1.0 (winrate: 52% pickrate: 1%)Chaos Knight
* Reality Rift lets Chaos Knight bypass the Spirit Bear and jump onto Lone Druid.
* The Spirit Bear's lack of scaling means it dies quickly to Chaos Knight during the late-game.
Bounty Hunter
[wiki] rating: -1.0 (winrate: 52% pickrate: 8%)Chaos Knight
* Phantasm dispels 
Track, and the illusions make it difficult to Track the real Chaos Knight.
* Bounty Hunter is fragile and can easily be killed by Chaos Knight and Phantasm's illusions.
Razor
[wiki] rating: -1.0 (winrate: 53% pickrate: 2%)Chaos Knight
* Razor has no way to deal with Chaos Knight's multiple illusions from Phantasm.
Ogre Magi
[wiki] rating: -1.0 (winrate: 53% pickrate: 17%)Chaos Knight
* Phantasm dispels Ignite and makes targeting the real Chaos Knight much harder.
Faceless Void
[wiki] rating: -0.6 (winrate: 44% pickrate: 8%)Keeper of the Light
* Any hero that can nullify effects of Chronosphere: (Omniknight, Keeper of the Light with Aghanim's Scepter during daytime, 
Winter Wyvern), banishing him or Faceless Void (
Outworld Destroyer, 
Shadow Demon, 
Earth Spirit with Aghanim's Scepter) or protecting him in other ways (
Dazzle, Oracle, 
Abaddon) can greatly limit Chronosphere's potential.
Doom
[wiki] rating: -0.6 (winrate: 44% pickrate: 3%)Chaos Knight
* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.
Terrorblade
[wiki] rating: -0.6 (winrate: 46% pickrate: 6%)Keeper of the Light
* Heroes that can stall pushes: Invoker, Keeper of the Light, Lina, Luna.
Shadow Demon
[wiki] rating: -0.6 (winrate: 46% pickrate: 3%)Chaos Knight
* Chaos Knight, 
Lone Druid, Meepo and Arc Warden can be hard targets since Shadow Demon's spells are ill-suited to fight many enemies at once.
Nature's Prophet
[wiki] rating: -0.6 (winrate: 47% pickrate: 4%)Keeper of the Light
* Heroes that have AoE damage: Lina, Keeper of the Light, 
Timbersaw, 
Leshrac, 
Bristleback, 
Axe
Vengeful Spirit
[wiki] rating: -0.6 (winrate: 48% pickrate: 9%)Chaos Knight
* Heroes who relies on illusions and summons (Beastmaster, Chaos Knight, etc.).
Disruptor
[wiki] rating: -0.6 (winrate: 49% pickrate: 8%)Chaos Knight
* Chaos Knight with Phantasm
* Heroes that can dodge Glimpse:
* Puck with 
Phase Shift
* Riki with 
Tricks of the Trade
* Phantom Lancer with Doppelganger
* 
Ember Spirit with 
Sleight of Fist and 
Activate Fire Remnant
* Chaos Knight with Phantasm
* Naga Siren with 
Mirror Image
* 
Tusk with 
Snowball
* Juggernaut with 
Omnislash
* 
Brewmaster with 
Primal Split
* 
Lifestealer with 
Infest
* Phoenix with 
Supernova
Additional:
* Phantasm removes 
Glimpse and dispels 
Thunder Strike. Additionally, the Phantasm illusions make it difficult to use Glimpse and Thunder Strike on the real Chaos Knight.
* Disruptor's lack of mobility, combined with his lack of innate defense, sets him up for a Reality Rift and a beatdown by Chaos Knight and his illusions.
Luna
[wiki] rating: -0.6 (winrate: 49% pickrate: 4%)Chaos Knight
* Heroes that create illusions (such as Spectre, Shadow Demon, Phantom Lancer, Naga Siren, Chaos Knight, Terrorblade) or bring other units into the fight (such as 
Nature's Prophet, Lone Druid, 
Chen, 
Enchantress and the aforementioned Meepo and Arc Warden) can cause Eclipse to strike the illusions/summons unintentionally. (However, in many cases Moon Glaives can resolve this issue and eliminate them before activating Eclipse).
Clockwerk
[wiki] rating: -0.6 (winrate: 50% pickrate: 7%)Chaos Knight
* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.
Skywrath Mage
[wiki] rating: -0.6 (winrate: 50% pickrate: 6%)Chaos Knight
* Skywrath mage also has a terrible time fighting against anything that isn't a hero. As Mystic Flare only affects heroes, his skills are mostly target-based and he has terrible strength and agility, he can easily be kited or harassed by illusion-based heroes like Chaos Knight and Phantom Lancer, or by Heroes that summon other units like Lone Druid, 
Lycan and Beastmaster.
Chen
[wiki] rating: -0.6 (winrate: 50% pickrate: 1%)Chaos Knight
* Illusion and heroes with summons are difficult to kill with Chen's single-target offensive spells: Terrorblade, Phantom Lancer, Chaos Knight, Broodmother, Naga Siren, Lycan, Visage. However, Chen can convert enemy summons with Holy Persuasion, as long as they don't bunch up.
Undying
[wiki] rating: -0.6 (winrate: 50% pickrate: 7%)Chaos Knight
* Chaos Knight's multiple illusions from Phantasm can destroy Undying, as Soul Rip can't offset the damage from the high amount of damage from his illusions.
Ursa
[wiki] rating: -0.6 (winrate: 50% pickrate: 12%)Chaos Knight
* Ursa struggles against illusion heroes like Chaos Knight and Phantom Lancer.
Additional:
* Ursa cannot effectively fight against Phantasm's illusions with his single-target damage.
* Chaos Bolt's potentially long stun with Chaos Bolt gives Ursa little opportunity to 
Enrage.
Bloodseeker
[wiki] rating: -0.6 (winrate: 51% pickrate: 2%)Chaos Knight
* Heroes with illusion and clone abilities may confuse Bloodseeker, causing him to waste time in fights: Phantom Lancer, Chaos Knight, Arc Warden
Bane
[wiki] rating: -0.6 (winrate: 51% pickrate: 5%)Chaos Knight
* Heroes with illusions and summons can swarm Bane, who has no area abilities: Broodmother, Chaos Knight, Nature's Prophet, Phantom Lancer, Terrorblade
Additional:
* Phantasm's illusions make it difficult for Bane to target Chaos Knight with 
Nightmare, 
Brain Sap and 
Fiend's Grip.
* Chaos Bolt is a comparatively low cooldown tool to interrupt Fiend's Grip.
* Nightmare can be transferred by Phantasm illusions.
Spirit Breaker
[wiki] rating: -0.6 (winrate: 51% pickrate: 8%)Keeper of the Light
* Heroes that punish mobile heroes: Bloodseeker, Keeper of the Light
Warlock
[wiki] rating: -0.6 (winrate: 51% pickrate: 5%)Chaos Knight
* Warlock is a very strong hero when positioned correctly, and his long cast range helps him with this. However, some Heroes might disrupt or sneakily pass through your allies and deal with you, preventing you from doing your job. Such heroes include Chaos Knight, 
Spirit Breaker, Riki, and some others.
Visage
[wiki] rating: -0.6 (winrate: 51% pickrate: 3%)Chaos Knight
* Heroes that can overwhelm Visage by sheer number like Chaos Knight, Meepo, Terrorblade and Phantom Lancer.
Shadow Shaman
[wiki] rating: -0.6 (winrate: 52% pickrate: 13%)Chaos Knight
* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.
Juggernaut
[wiki] rating: -0.6 (winrate: 53% pickrate: 20%)Keeper of the Light
* Juggernaut's Healing Ward keeps his team healthy even when pushing against Keeper of the Light's Illuminate.
* Blade Fury can dispel Blinding Light, as well as dodge an incoming Illuminate. Juggernaut can attack towers during Blade Fury, so he can dodge an Illuminate without having to stop pushing.
* Keeper of the Light has low health, low armor, and no natural defense against Omnislash.
Keeper of the Light
* Keeper of the Light's Blinding Light makes Juggernaut miss his attacks.
Chaos Knight
* While Blade Fury is on cooldown, Juggernaut can easily killed by a standard Chaos Bolt & Reality Rift combo.
* Phantasm illusions can tank Omnislash.
Lycan
[wiki] rating: -0.6 (winrate: 57% pickrate: 6%)Keeper of the Light
* Keeper of the Light has a blind, which causes Lycan to miss his attacks.
Lifestealer
[wiki] rating: 0.0 (winrate: 45% pickrate: 5%)Keeper of the Light
* 
Rage allows him to dispel Blinding Light from himself.
* 
Open Wounds allows him to slow and kill Keeper of the Light.
Chaos Knight
* Chaos Knight's Level 20 Talent: Reality Rift Pierces Spell Immunity allows for quick bursting down of Lifestealer during his Rage.
* Phantasm dispels Open Wounds.
* Lifestealer has no way of dealing with Chaos Knight's illusions.
Phantom Assassin
[wiki] rating: 0.0 (winrate: 46% pickrate: 17%)Keeper of the Light
* Heroes with teleports to escape Will-O-Wisp: Phantom Assassin, Puck, Queen of Pain, Storm Spirit
Chaos Knight
* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them: Broodmother, Phantom Lancer, Chaos Knight.
Huskar
[wiki] rating: 0.0 (winrate: 49% pickrate: 2%)Keeper of the Light
* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: 
Lich, 
Crystal Maiden, 
Silencer, Keeper of the Light, Venomancer, etc.
Chaos Knight
* Heroes with illusions can overwhelm Huskar, as he has no AoE abilities: Phantom Lancer, Anti-Mage, Arc Warden, Chaos Knight.
Necrophos
[wiki] rating: 0.0 (winrate: 49% pickrate: 4%)Chaos Knight
* Heroes that have high health but little to no magic resistance are easy prey for Necrophos, as no matter how high they build their health up, Reaper's Scythe will kill them outright as long as they fall under a certain threshold, and Heartstopper Aura will deal the same amount of damage regardless, decaying their health the longer they stay within range. As such, Strength heroes like Chaos Knight, 
Centaur Warrunner or 
Magnus are good targets for his ultimate.
Chaos Knight
* Illusions make it difficult for Necrophos to target his Reaper's Scythe correctly, thus giving illusion heroes like Chaos Knight or Naga Siren an edge against Necrophos.
Templar Assassin
[wiki] rating: 0.0 (winrate: 49% pickrate: 5%)Keeper of the Light
* Heroes that can jump and kill him: Meepo, Clinkz, Templar Assassin
Chaos Knight
* Multiple attackers thanks to illusions: Phantom Lancer, Chaos Knight, Naga Siren (bonus for her 
Ensnare). Also despite the visual effects, Templar Assassin does not spill damage against illusions or buildings, so she is not a really good hero to clean up illusions.
* Heroes that can quickly deal damage to her, regardless of how weak they are, can easily break through her Refraction:
* Multiple attackers thanks to summoned units or clones: Meepo, 
Witch Doctor, Lycan, Enigma, Shadow Shaman
* Multiple attackers thanks to illusions: Phantom Lancer, Chaos Knight, Naga Siren (bonus for her Ensnare). Also despite the visual effects, Templar Assassin does not spill damage against illusions or buildings, so she is not a really good hero to clean up illusions.
* Weak damage but high tick rate or persist in a long time: Slark, 
Gyrocopter, Queen of Pain, Shadow Shaman (
Shackles), Pugna
Crystal Maiden
[wiki] rating: 0.0 (winrate: 50% pickrate: 13%)Chaos Knight
* Heroes the make heavy use of illusions, like Chaos Knight, Phantom Lancer, or Spectre can suffer from Crystal Maiden, as Freezing Field can quickly kill off the entire horde if not stopped.
Chaos Knight
* Innately fragile heroes will die almost instantly to Reality Rift while Chaos Knight has illusions active: 
Drow Ranger, Bane, 
Necrophos, Crystal Maiden.
Pangolier
[wiki] rating: 0.0 (winrate: 51% pickrate: 7%)Chaos Knight
* 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
Keeper of the Light
* Certain heroes can mess up with Pangolier's positioning and timing (especially if he intends to use Rolling Thunder during combat): 
Vengeful Spirit, Keeper of the Light, Huskar, 
Dark Seer
Night Stalker
[wiki] rating: 0.0 (winrate: 53% pickrate: 5%)Keeper of the Light
* 
Crippling Fear prevents Keeper of the Light from using his spells to keep his team alive during team-fights.
* 
Dark Ascension is very strong against Keeper of the Light, who relies on daytime to be effective.
Additional:
* Keeper of the Light's Aghanim's Scepter upgrade loses much of its power, due to Night Stalker being able to reduce the duration of daytime by a lot.
Chaos Knight
* Reality Rift pulls out Night Stalker while he tries to escape or chase.
* Night Stalker doesn't have a lot of ways to deal with multiple targets, which makes him vulnerable to Phantasm illusions from early to mid game, until Night Stalker buys Aghanim's Scepter.
Enigma
[wiki] rating: 0.0 (winrate: 53% pickrate: 4%)Chaos Knight
* 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.
Keeper of the Light
* Ezalor's Chakra Magic will drain Enigma's mana pool rather quickly and won't let him chase or initiate with Black Hole properly.
* Will-O-Wisp will disable any close caster like Enigma, forcing him have to keep his Eidolons at maximum count and keep a safe distance.
* Illuminate can wipe the pushing Eidolons in a lane with ease, diminishing your laning presence by a lot.
Monkey King
[wiki] rating: 0.0 (winrate: 54% pickrate: 18%)Chaos Knight
* 
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.
Keeper of the Light
* Blinding Light can easily push Monkey King out of Wukong's Command, as well as blinding him.
* Will-O-Wisp destroys trees in a massive area, damaging Monkey King's mobility
* However, Keeper of the Light can be easily ganked by Monkey King during early-mid game stage.
Additional:
* Blinding Light can knock Monkey King outside of his ultimate, Wukong's Command or can generally blind him effectively.
* Will-O-Wisp stun Monkey King from Tree Dance by destroying his tree.
Chaos Knight
* 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.
*
Keeper of the Light
* Low health spellcasters:
Lina, 
Witch Doctor, 
Tinker, 
Keeper of the Light, all rely heavily on their spells and are fragile heroes. They all also have avoidable spells, allowing Puck to get to them and quickly burst them down.