* 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.

* Slark's dependence on Pounce and close range makes him very easy to hit with Purification.
* Slark's damage, even with a high count of Essence Shift, is easily negated by Omniknight's heals and Guardian Angel.

* 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.

* In team fights, Guardian Angel renders Drow Ranger's physical damage useless.

* Heavenly Grace reduces Fireblast stun time and dispels Ignite.
* Purification can heal damaged hero if needed.

* Phantasm dispels Ignite and makes targeting the real Chaos Knight much harder.

* While Blade Fury is on cooldown, Juggernaut can easily killed by a standard Chaos Bolt & Reality Rift combo.
* Phantasm illusions can tank Omnislash.

* Guardian Angel completely negates all physical damage, including Omnislash.
Additional:
* Omnislash is blocked by Guardian Angel.

* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.

* Purification does great damage to Clockwerk when fighting an enemy inside Power Cogs.
* For the same reasons, Omniknight also makes a powerful ally for Clockwerk when the situation is reversed.

* Heroes with illusion and clone abilities may confuse Bloodseeker, causing him to waste time in fights: Phantom Lancer, Chaos Knight, Arc Warden

* Guardian Angel's near invulnerability denies Bloodseeker the bonuses from Thirst, preventing him from gaining the upper hand in teamfights.
* Purification's pure damage makes it hard for Bloodseeker to pursue enemies, and prevents him from replenishing his health by finishing off enemies.

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

* 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.

* 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.

* Omniknight with Heavenly Grace
* Heroes that can remove the Track debuff with their skills:
* Abaddon with Aphotic Shield and Borrowed Time
* Huskar with Life Break
* Juggernaut with Blade Fury
* Legion Commander with Press the Attack
* Lifestealer with Rage and Infest
* Naga Siren with Mirror Image
* Omniknight with Heavenly Grace
* Oracle with Fortune's End and False Promise
* Phantom Lancer with Doppelganger
* Slark with Dark Pact
* Ursa with Enrage
* Weaver with Time Lapse
* Tidehunter with Kraken Shell when damage received reaches the threshold.

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

Additional:
* Purification easily catches Phantom Assassin when she jumps in to attack.
* Guardian Angel renders Phantom Assassin useless, as she depends entirely on physical attacks.

* 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.

* 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.

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

* 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.

* Heroes with dispels can dispel Bane's disables from their allies: Oracle, Legion Commander, Omniknight

* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.

* Omniknight can dispel Hex or Shackles with Heavenly Grace. He can also heal teammates which you disabled. The same goes to Abaddon's Aphotic Shield .

* 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.

* Global Guardian Angel will protect his allies from Spectre's Haunt, both when they are alone and in teamfights.
* Purification is a major problem for melee enemies, Spectre included, since they must be next to an enemy in order to attack. The AoE damage also allows Spectre to be singled out from her illusions.
* Degen Aura will prevent Spectre from chasing Omniknight, further exacerbated by her terrible mobility outside Haunt.

* Being mostly a physical damage dealer, Sniper's effectiveness is greatly reduced by Omniknight's Guardian Angel.
* Omniknight's Degen Aura allows him to slow sniper and catch him. Sniper has to then use some escape item.
* Omniknight can also protect an ally from being finished off by Assassinate by using Purification.

* 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!.

* 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.

* 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.

* 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.

* 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.

* Purification allows Omniknight to keep a hero trapped in the Static Storm alive.

* Riki takes a lot of damage from Purification while ganking Omniknight's allies or himself.
* Heavenly Grace instantly purges the slow from Diffusal Blade, while also providing a large amount of survivability for his victim.
* Degen Aura can hinder Riki's positioning tactics and put a heavy toll on Riki's already poor movement speed.
* Omniknight can easily save his allies by using Guardian Angel in combat.

* In the early game, Omniknight can look like an easy target for Spirit Breaker, but with Purification and Degen Aura, what could be an opportunity could quickly turn into disaster.
* Heavenly Grace can be used to counter Charge of Darkness by minimizing the damage and lowering the stun duration with status resistance.
* Spirit Breaker's Greater Bash from all sources (Charge of Darkness or normal attacks) deals lesser damage if he is within the radius of Degen Aura.
* Due to this, Spirit Breaker's damage will always be lower when targeting Omniknight.

* Exorcism's damage is blocked by Guardian Angel.
Additional:
* Degen Aura reduces Death Prophet's movement speed, keeping her in range.
* Guardian Angel nullifies the physical damage from Exorcism.

* 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.

* 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.

* Razor has no way to deal with Chaos Knight's multiple illusions from Phantasm.

* 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.

* 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.

* Heroes that can save their allies can be a big problem for Mars: Dazzle, Omniknight.

* Heroes who relies on illusions and summons (Beastmaster, Chaos Knight, etc.).

* 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.

* Omniknight: An undispellable Heavenly Grace can easily save a victim of Shadow Demon.

* 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.

* 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.

* Heroes who possess abilities that can save targets from being killed by Reaper's Scythe: Abaddon, Bane, Outworld Destroyer, Shadow Demon, Omniknight, etc.

* 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.

* 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

* Heroes with illusions can overwhelm Huskar, as he has no AoE abilities: Phantom Lancer, Anti-Mage, Arc Warden, 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.

* Heroes that can overwhelm Visage by sheer number like Chaos Knight, Meepo, Terrorblade and Phantom Lancer.

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

Additional:
* Guardian Angel completely negates all of Lycan's damage since Lycan mainly deals physical damage.
* Purification can also be a problem for Lycan, as Purification deals damage around the target, which poses a problem for him and his summons.

* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.

* Heavenly Grace dispels the stun from Ink Swell, and greatly reduces Soulbind's duration.
* Purification can turn the tables on enemies trying to get close to stun with Ink Swell.

* 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.

* Both Guardian Angel and Purification are perfect counters against Duel.
Additional:
* Purification prevents Legion Commander from killing her target, and will always hit her during Duels.
* Guardian Angel completely wastes Duel's duration, and can save an ally across the map when upgraded with Aghanim's Scepter.

* 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.

* Heroes with the ability to heal allies, or those with good defensive abilities: (Chen, Dazzle, Io, Oracle, Omniknight, Witch Doctor, Winter Wyvern, (Abaddon, etc.

* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.

* Guardian Angel makes allies immune to all physical damage, effectively causing Tidebringer to do no damage.
* Purification is a powerful, pure damaging heal that can save Omniknight's allies after Kunkka's large damage.

* The pure damage provided by Purification is a great addition for killing Ember Spirit, as well as a good way of saving teammates.
* Guardian Angel will temporarily save his allies from Sleight of Fist's physical damage, and Ember Spirit is not a hero that will get Orchid Malevolence to counter it.

* Guardian Angel protects allies from Death Ward's physical damage.
* Purification and Heavenly Grace will most likely save teammates from dying to Maledict.

* 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.

* Omniknight's healing prevents allies from dropping low enough for Culling Blade. However, it can still go through all his buffs.
* Axe also enjoys getting close to allied heroes in order to damage them with his Counter Helix, which can easily be punished by Purification.

* Guardian Angel negates most of Gyrocopter's physical АоЕ damage.
* Heavenly Grace dispels Homing Missile stun.

* 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.

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

* Guardian Angel completely counters Winter's Curse if he is able to cast it.
Additional:
* Guardian Angel completely counters Winter's Curse, allowing his team to survive Winter Wyvern's initiation.
* Purification and Heavenly Grace are very useful against Arctic Burn and Splinter Blast as well.