* 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!.

* Plague Wards may reveal a hiding Techies. If there's a sentry nearby, they may also reveal a stack of mines hidden in a juking spot.

* Venomancer's magical damage-over-time poisons greatly reduce Bounty Hunter's mobility.
* Venomous Gale, Plague Wards and Poison Nova with True Sight items can allow Venomancer and his teammates to gank Bounty Hunter while he is roaming alone.

* 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.

* 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

* Windranger's Focus Fire tears apart Templar Assassin's refraction very quickly and easily bursts her down due to her low health pool against Windranger's immense attack speed
* Templar Assassin's "Psionic Trap" doesn't slow down Windranger due to her skill Windrun
* Templar Assassin's high damage can also be easily evaded thanks to Windrun's 100% evasion
Additional:
* Venomous Gale and Plague Wards allow to quickly melt through Refraction charges.
* Both Poison Nova and Venomous Gale hit invisible units, so Meld cannot be used defensively.

* Venomous Gale, Poison Sting and Poison Nova deal damage over time and will chip away at Gravekeeper's Cloak in addition to slowing an already sluggish hero.
* Venomancer's normal attacks deal Poison Sting and will chip away at Gravekeeper's Cloak.

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

* Untouchable won't mitigate Venomancer's magical damage, and Enchantress is vulnerable to magic damage.
* Both Venomous Gale and Poison Nova lowers the amount of healing received by Enchantress and her allies from Nature's Attendants.

* 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.

* 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.

* Venomancer's damage over time can force Chen to use Hand of God prematurely, potentially wasting a chance to save his allies during a teamfight.

* Venomancer's poison damage-over-time are very effective against Spectre, which is lack of magic resistance from early to mid game.
* Venomancer's multiple slows greatly reduces Spectre's low mobility, even through Spectral Dagger.
* Plague Wards reveals Spectre while she is hiding on trees.
Additional:
* Venomancer's poison damage over time is very effective against Spectre, who tends to lack magic resistance during the early to mid game.
* Venomancer's multiple slows greatly reduces Spectre's movement speed and mobility.
* Plague Wards can scout out Spectre while she is hiding in trees.

* Venomancer's spells all deal magical damage, ignoring Bulwark.
* Venomancer's multiple slows are especially effective at kiting Mars.
* Plague Wards can attack through Arena Of Blood.
Additional:
* Venomancer's poison attacks are all magical damage, ignoring Bulwark.
* Venomancer's multiple slows are especially effective against Mars' low mobility.
* Plague Wards can attack through Arena of Blood.

* 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.

* 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.

* 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'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.

* Plague Wards are very hard for Batrider to play against as they provide a lot of vision as well as disable Blink Dagger for a long duration.

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

* 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.

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

* 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.

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

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

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

* 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.

* 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 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).

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

* Heroes that can slow Charge of Darkness by a huge amount: Venomancer, Viper, Dazzle, Arc Warden

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

* 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 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.

* 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.

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

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

* Aggressively Poofing and Earthbinding is not going to end well against Venomancer, as he will be an easy target for Poison Nova.
* Venomancer constant slows greatly reduce Meepo's 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.

* 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.

* Venomancer forces Sven to choose between using his Black King Bar or getting constantly slowed by his poison.

* Venomancer can simultaneously scout Magnus hiding in trees and putting Blink Dagger on cooldown with Plague Wards, which makes Magnus real problems to blink and initiate.
Additional:
* Similar to Night Stalker, Venomancer can simultaneously scout Magnus hiding in trees and put Blink Dagger on cooldown with Plague Ward, which gives Magnus problems when trying to blink in and initiate.

* 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.

* 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.

* 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.

* 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.

* Venomancer's slows and magical damage-over-time work well against Axe's complete lack of mobility.
* Plague Ward is especially useful for slowing down Axe, and revealing him before he initiates, as well as putting his Blink Dagger on cooldown.
Additional:
* Venomancer's slows and magical damage-over-time work well against Axe's complete lack of mobility.
* Plague Wards is especially useful for slowing down Axe, and revealing him before he initiates, as well as putting his Blink Dagger on cooldown.
* For the same reasons, Venomancer is a good ally for Axe when the situation is reversed.

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

* Since Windranger is bad against magical damage, heroes with continuous magical damage or magical nukes can blast her: Zeus, Tinker, Leshrac, Viper, Skywrath Mage, Lion, Lina, Venomancer.

Additional:
* Due to lack of magic resistance, Venomancer poisons eats through Windranger's health.

* Venomancer's slows and magical damage-over-time works well against Earthshaker's which completes lack of mobility.
* Plague Wards is useful for slowing and kitting down Earthshaker, revealing him from initiating and re-initiating and putting his Blink Dagger on cooldown if Venomancer has vision over Earthshaker.
Additional:
* Earthshaker can be kited by Venomancer's slows, which is lack of mobility.
* Plague Wards is very useful for slowing and kitting down Earthshaker, revealing him from initiating and re-initiating and putting his Blink Dagger on cooldown.

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

* Venomancer's magical damage-over-time poisons will constantly put Tree Dance on cooldown, greatly diminishing Monkey King's mobility.
* Venomous Gale and Poison Nova will hit Monkey King when he is perched on a tree, or disguised with Mischief.
* However, Venomancer is also easily ganked by Monkey King if caught by surprise.
Additional:
* Venomancer's magical damage-over-time poisons putting Tree Dance on cooldown, greatly diminishing Monkey King's mobility.
* Venomous Gale and Posion Nova will hit Monkey King when he is perched on a tree, or disguised by Mischief.

* 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.

* Unless Puck is facing the direction he wants to blink while in Phase Shift, the Venomous Gale and Poison Nova combo consistently ticks many times over several seconds, making it very difficult to use Blink Dagger towards the other direction. Puck's slow turning rate makes this even worse.