* 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.

* Thunder Strike provides vision on him while Slark is invisible.
* Glimpse's range at lvl 3-4 is more than enough to pull him back to a favorable position for your team to group up and kill him.
* Even though he is capable of picking you off and deal enough damage to kill you, Slark will be literally sticking his neck out, since jumping on Disruptor means being on his battleground.
* AoE silence and the ability to mute Black King Bar is deadly to Slark at all stages of the game.
Additional:
* Static Storm and Kinetic Field locks down Slark, as he cannot use Dark Pact to dispel any disables, or Pounce out while silenced.
* Glimpse puts an end to any attempts at ganking Disruptor or his allies, and also negates Slark's mobility by bringing him back into the fight if he tries to escape with Pounce.

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

* Glimpse moves Clockwerk away from allies struck by Hookshot, or under attack by Battery Assault.
* Static Storm can turn Power Cogs into Clockwerk's own grave, but Blade Mail will also return the damage to Disruptor.

* 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.

* As a spellcaster, silences will nullify him entirely. Some notable examples are Death Prophet, Drow Ranger, Bloodseeker, Disruptor and many others.
* Doom, as usual, fits this description nicely.

* Ursa struggles against heroes with strong (and especially undispellable) disables (Disruptor, Puck, Shadow Demon, Outworld Devourer and etc).

* 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 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.

* Doom, Disruptor with Aghanim's Scepter, and hex abilities all prevent item usage, which is a severe problem for Phantom Assassin as it prevents her from using Black King Bar, the one item that helps protect her against the aforementioned dangers. Doom and Shadow Demon with Aghanim's Scepter also disables Phantom Assassin's Evasion and Critical Strike, removing much of her damage and survivabaility.

* Glimpse directly negates Relocate.
Additional:
* 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.

* 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.

* 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.

* 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!.

* Blink and positioning is crucial for Queen of Pain. These factors are heavily countered by a good Glimpse.
* Static Storm is devastating for Queen as she relies heavily on her spells to inflict heavy burst damage.
Additional:
* Thunder Strike gives vision of Queen of Pain when she's trying to escape. When combined with Glimpse, her mobility and hit-and-run style can be negated.
* While in a team fight, Static Storm forces Queen of Pain to only use right-clicks.
* When combined with the Kinetic Field, she can only wait until she respawns.

* Glimpse and Kinetic Field allows Disruptor to set up some early kills onto Shadow Fiend.
* Static Storm can be used to cancel the cast of Requiem of Souls.

* 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.

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

* 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.

* 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.

* At around the 10-minute mark, Disruptor would normally be level 6 or 7. This means you can have a level 3/4 glimpse along with Static Storm. A high level glimpse is enough to pull Storm back to a Static Storm even after he used Ball Lightning due to his limited mana pool at that time.
* Be careful in the late game however, as there is a good chance he will kill you straight-out before Glimpse has finished bringing him back. Therefore Glimpse would simply bring him back to safety after he's murdered you or a teammate. Of course, this is assuming he hasn't silenced you with an item.

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

* Glimpse brings Anti-Mage back after he Blinks away.
* Static Storm stops Anti-Mage from Blinking.
Additional:
* Similar to Queen of Pain, Glimpse can disable Blink, negating his mobility.
* However, Counterspell can negate a majority of Disruptor's damage, which may require him to have a partner to successfully kill Anti-Mage.

* 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.

* 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.

* 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.

* 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.

* Glimpse will return Underlord or any of his teammates attempting to escape with Dark Rift if timed correctly.
* Underlord is a slow and low mobility hero, easy to set up Static Storm and Kinetic Field, preventing him from using his abilities as well as preventing him using Dark Rift to escape

* Heroes with detection: Bounty Hunter, Disruptor, Razor, Slardar, Spectre, Spirit Breaker

* 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.

* 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.

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

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

* 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).

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

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

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

* 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.

* 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.

* Disruptor can control where she goes with Kinetic Field and Glimpse. Static Storm shuts her down in teamfights.

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

* Glimpse can return Tusk to where he was after using Snowball.

* Kinetic Field and Glimpse can completely negate Stampede.

* 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.

* Thunder Strike provides vision of Monkey King when he's in the trees. The periodic damage will also keep Monkey King from using Tree Dance if he's on the ground.
* Glimpse pulls Monkey King out of the trees if he attempts to escape using Tree Dance, and can cause Wukong's Command to end prematurely if Monkey King is Glimpsed out of its radius.
* Kinetic Field and Static Storm can be used to hold Monkey King in place and ensure a kill.

* 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.

* Disruptor can disable Magnus's Blink Dagger using Thunder Strike during a considerable duration, disrupting his initiation attempts.
* Glimpse brings Magnus back after he escapes with Skewer and/or Force Staff.
* Static Storm if used on a fight can prevent Magnus from using Reverse Polarity after he jumps in.

* Thunder Strike can be used to cancel Earthshaker's Blink Dagger.
* Glimpse brings Earthshaker back after he jumps on Aghanim's Scepter upgraded Enchant Totem.
* Static Storm if used on a fight can prevent Earthshaker from executing his combo after blinking in.

* 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.

* In the mid-game, Tidehunter relies on Kraken Shell to stay alive and get his Ravage off. Apart from Thunder Strike, none of Disruptor's abilities can be dispelled, so it's rather easy to trap him inside Kinetic Field and Static Storm.
* Be mindful, however, that Kraken Shell still makes Tidehunter very tanky, so be sure that you can kill him with your combo or your partners while he is silenced and trapped.

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

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

* 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.

* 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.

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

* Dark Seer relies on Surge for most of his mobility, so he's not very vulnerable to slows, but much more to root effects and walls or pseudo-walls such as Disruptor's Kinetic Field or Slark's Pounce.