Chaos Knight
* Anti-Mage commonly builds 
Battle Fury, which can deal with Phantasm illusions easily.
* 
Counterspell, if timed right, will turn Chaos Bolt against Chaos 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 low amount mana.
* However, beware Anti-Mage is fairly fragile and cannot withstand heavy incoming physical damage at any points in the game, which Chaos Knight excels at. A good player will bait out Counterspell, and retaliate once it's over.
Phoenix
* Anti-Mage dispels Phoenix's slows with 
Manta Style.
* Anti-Mage can Blink directly next to 
Supernova, giving him more time to destroy the egg.
Chaos Knight
* Abaddon could punish Chaos Knight for using his Phantasm and Reality Rift combo on him with 
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, effectively reducing the amount of targets Chaos Knight can threaten by 1 for the entire game.
Phoenix
* Heroes that deal damage over time will also fail to bring down Abaddon and his allies, such as 
Huskar, 
Venomancer, or 
Phoenix.
Chaos Knight
* Heroes reliant on illusions or summons: 
Broodmother, 
Chaos Knight, 
Naga Siren.
Phoenix
* 
Lil' Shredder will make quick work of Supernova.
* 
Mortimer Kisses can easily hit a Phoenix using 
Sun Ray.
Chaos Knight
* 
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 long duration.
Additional:
* 
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.
Phoenix
* Phoenix does significant magic damage over time which can either be dispelled or negated by Fate's Edict.
* Oracle's burst damage potential can prove lethal to Phoenix, as they already have to sacrifice health to cast their basic skills.
Chaos Knight
* 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.
Additional:
* 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.
Chaos Knight
* 
Cold Embrace protects targets affected by 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 high max 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.
* Chaos Knight's high health pool and tendency to not build magic resistance items will make Arctic Burn deal a lot of damage to him and his illusions.
Phoenix
* Spiked Carapace reacts on any of the damage over time from Phoenix's abilities and can interrupt Sun Ray and 
Icarus Dive.
Phoenix
* Marci can destroy Supernova by herself with Unleash at any stage of the game.
* Phoenix is squishy hero with low armor and is very vulnerable for Rebound and Sidekick at the laning stage.
Chaos Knight
* 
Black Hole usually catches Chaos Knight with all his illusions.
* 
Midnight Pulse deals damage based on current health, quickly killing Phantasm illusions.
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 Phantasms early on, and can still deal a lot of damage to them late game, revealing the real Chaos Knight.
Phoenix
* Silencer will most likely disrupt an initiation with his ultimate, 
Global Silence, prevent escape with his 
Last Word, and if Phoenix happens to die to him (or near him) enough times, he would sap enough of Phoenix's much needed Intelligence to make him a stronger foe and Phoenix with less mana than it already had.
Phoenix
* Chemical Rage kills Phoenix very quickly in Supernova.
Phoenix
* Earthbind can prevent Phoenix from using Icarus Dive, the only escaping mechanism of this hero.
* Heavy burst damage from Poof can easily kill Phoenix even when it slows down all the Meepos with 
Fire Spirits.
* Meepo's clones destroy the Phoenix Sun from Supernova in no time, even when they are slowed down by Fire Spirits.
* Meepo's naturally high magic resistance gives Phoenix a hard time with bursting him down. He can even turn the tide if Icarus Dive is on cooldown.
Additional:
* Meepo is unlike any other multi-unit enemy Phoenix may face in the battlefield. Unlike illusion-based heroes like 
Phantom Lancer or Chaos Knight, Meepo's clones are not illusions, meaning they can deal full damage to the Phoenix Sun if all four (or five) are present.
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.
Phoenix
* Phoenix constantly depletes its own health due to the health costs of its abilities. Unlike heroes that have a similar mechanic, Phoenix does not benefit from low health, nor does it really have a countermeasure for it. As such, Phoenix is a very vulnerable target for Necrophos to prey on, especially when caught off guard before it can cast Supernova.
Additional:
* Necrophos becomes a bigger threat the lower one's health gets, and unfortunately for Phoenix, most of its spells have noticeable health costs. Those costs, coupled with his 
Heartstopper Aura, means that staying in a teamfight for too long under Necrophos' presence will make Phoenix a more valid target for his ultimate, with its stun completely preventing any form of retaliation or protection. Necrophos players are also likely to buy more durability items such as 
Hood of Defiance, making him more able to withstand Phoenix's damage despite having no escape mechanisms.
* However, it is also important to remember that a Scepter-upgraded Supernova can help protect an ally from his ultimate.
Chaos Knight
* Innately fragile heroes will die almost instantly to Reality Rift while Chaos Knight has illusions active: 
Drow Ranger, 
Bane, 
Necrophos, 
Crystal Maiden.
Chaos Knight
* 
Ravage damages and disables Chaos Knight and his illusions.
* 
Anchor Smash deals respectable area damage, especially to Phantasms and lowers Chaos Knight's damage output.
* 
Kraken Shell dispels Chaos Bolt and Reality Rift while providing protection from damage.
Chaos Knight
* 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 harder to kill.
Additional:
* 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.
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:
* 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.
Chaos Knight
* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: Naga Siren, Phantom Lancer, Broodmother
Phoenix
* 
Song of the Siren does not affect Supernova, which allows her and her team to focus the egg while the enemy team is affected by sleep.
* Phoenix cannot use Icarus Dive for escaping when rooted by 
Ensnare.
* However, Phoenix has many area-of-effect abilities that allow him to clear Naga Siren's illusions from 
Mirror Image.
Phoenix
* 
Sand King and Phoenix have many tools to deal with multiple enemies at once, which will work well against a crowd of illusions.
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.
Chaos Knight
* Flak Cannon destroys Chaos Knight's illusions very quickly.
Phoenix
* As a hero with uncommon traits, Phoenix's abilities require more health than mana. It is advised for Rubick to purchase health regeneration items such as 
Tranquil Boots, 
Urn of Shadows or Hood of Defiance to keep up with the HP loss.
* Phoenix's signature Supernova, if casted successfully, can turn a teamfight around if being stolen.
* The initial lift and the following crowd control from the drop of 
Telekinesis can protect the egg from being attacked if casted right before Supernova with quick fingers.
* A successfully reborn Supernova refreshes the cooldown of Telekinesis as well as 
Fade Bolt, so don't hesitate to spam both of them before Supernova with the reasons mentioned above.
* Supernova has a stun range of 1200, which requires Rubick to have Level 3 
Arcane Supremacy at least to exceed its range. Consider buying 
Aether Lens or 
Blink Dagger to help with positioning.
* It is not possible to cast Supernova (as of 7.31c) with 
Aghanim's Shard's extra Sun Ray even with both spell stolen, since Sun Ray takes up two stolen ability slots.
* Icarus Dive is a useful repositioning ability for scouting, initiation or escaping.
* Fire Spirits aids with Rubick farming given enough HP regeneration. In early skirmishes, the stolen ability can slow the attack speed of the enemy team to a crawl.
* Combined with Fade Bolt, both the attack damage and attack speed of the enemy team are reduced if they have no source of dispel, effectively nullifying their physical attack damage.
* Sun Ray thrives in and after a teamfight by damaging enemy heroes and healing allies at the same time.
* Rubick can interrupt both Icarus Dive and Sun Ray by casting Telekinesis.
Chaos Knight
* 
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.
Additional:
* 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 physical damage output.
Chaos Knight
* Techies has great area of effect damage to deal with Phantasm illusions.
* Blast Off silences Chaos Knight, stopping him from using his disables and allowing his teammates to walk away from his heavy damage.
* Reactive Tazer will disarm all of Chaos Knight's illusions even if he has activated his Black King Bar.
Chaos Knight
* 
Untouchable will significantly slow down Chaos Knight's physical damage with Phantasm.
* 
Impetus deals double damage to illusions, making it effective against Phantasm.
Additional:
* Untouchable makes all of Chaos Knight's attacks slow therefore he is unable to deal damage, especially his critical damage of 
Chaos Strike, also enables Enchantress to escape easily from his attacks.
* However, Reality Rift can still pose a danger to Enchantress because Chaos Knight can decrease a good amount of armor, making it dangerous because of her little armor stat, as he can burst down Enchantress easily if any of Chaos Knight's allies can apply a break on Enchantress.
Chaos Knight
* Illusion-based and multi-unit heroes can take advantage of Chaos Knight's lack of area damage: Naga Siren, Phantom Lancer, Broodmother
Chaos Knight
* Heroes who are entirely reliant on dealing physical damage and/or have very little to no area-of-effect abilities will make Underlord tickle and will have no effect against him thanks to his 
Atrophy Aura, and will also be unable to ambush Underlord and his team if Underlord chooses to use 
Fiend's Gate to get to a designated point of the map: 
Phantom Assassin, 
Terrorblade, 
Troll Warlord, Drow Ranger, Phantom Lancer, Chaos Knight, 
Sven, 
Wraith King, 
Bounty Hunter, 
Alchemist, 
Templar Assassin, 
Nyx Assassin, Bane.
Chaos Knight
* Heroes who are reliant on illusions: Chaos Knight, Phantom Lancer, Naga Siren.
Chaos Knight
* Most Illusion based heroes (like Chaos Knight and Terrorblade) can't use their illusion beneficially against Sanity's Eclipse's high AoE burst damage.
Chaos Knight
* 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.
Chaos Knight
* Heroes with Attack speed decreasing skills: 
Jakiro, 
Viper 
Lich
Phoenix
* 
Corrosive Skin gives Viper additional resistance to Phoenix's magical damage, and since they deal damage over time, Phoenix would be constantly afflicted by his passive's own debuff, making him not an ideal target for Phoenix's harassment. Phoenix's abilities also constantly drain its own health away, becoming more vulnerable to 
Poison Attack.
Chaos Knight
* As Viper focuses on single-target damage, he has trouble fighting off Phantasm illusions.
* Reality Rift counteracts Viper's slows and reduces his already low durability against physical damage.
Additional:
* Viper has no response to the standard initiation combo of Reality Rift into Chaos Bolt.
* Phantasm and Chaos Strike can eliminate Viper almost instantly with it's damage output.
* Besides Nethertoxin, Viper has no other ways of dealing with Phantasm.
Phoenix
* Any hero with high attack speed will be a threat to Phoenix when it initiates, as they can easily tear down a Supernova, perhaps even while debuffed by Fire Spirits: 
Juggernaut, 
Clinkz, Troll Warlord, 
Beastmaster, 
Lina.
Chaos Knight
* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: Phantom Lancer, Chaos Knight, Naga Siren, Terrorblade.
Phoenix
* Silence (and mana burns) will be a persistent problem for Phoenix, as it is heavily reliant on its abilities whether defensively or offensively, so heroes like 
Death Prophet, 
Skywrath Mage, and even Nyx Assassin must be closely observed to prevent being shut down by these heroes.
* Hexes are a greater threat to Phoenix as they also disable items, preventing Phoenix from dispelling the debuff on its own.
Chaos Knight
* Heroes with strong area damage to destroy Phantasm illusions: 
Axe, 
Ember Spirit, 
Legion Commander, Phoenix
Additional:
* 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.
Chaos Knight
* Once he buys Aghanim's Shard, Dazzle's 
Poison Touch can hex enemies, and hex can instantly kill illusions, making Dazzle strong against heroes who rely on illusions. Bear in mind that Chaos Knight is the exception because his Phantasms are strong illusions that are immune to abilities that can instantly kill illusions.
Phoenix
* Any hero with high attack speed will be a threat to Phoenix when it initiates, as they can easily tear down a Supernova, perhaps even while debuffed by Fire Spirits: Juggernaut, Clinkz, Troll Warlord, Beastmaster, Lina.
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
Chaos Knight
* Heroes who are reliant on illusions or summons: Chaos Knight, Broodmother, Naga Siren.
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.
Chaos Knight
* Illusion heroes, such as Naga Siren, Phantom Lancer, Chaos Knight, Terrorblade will become strong against Tinker in the late game. 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.
Phoenix
* Phoenix expends health to use its abilities, making it a good target for Thirst.
* Rupture deals heavy damage against Icarus Dive.
Additional:
* Although 
Blood Rite can be easily avoided, if it does hit, its lengthy silence and pure damage can be a severe punishment for a slow, unobservant, or simply unfortunate Phoenix.
* His 
Rupture can turn Icarus Dive into a suicide option, and it cannot be dispelled, meaning even if Phoenix completes a Supernova, choosing to Dive may just cut its health back down.
* And finally, due to Phoenix's health costs, too much careless ability spamming may just put Phoenix into Bloodseeker's vision through 
Thirst, making it a very tempting ganking target.
Chaos Knight
* Heroes with illusion and clone abilities may confuse Bloodseeker, causing him to waste time in fights: Phantom Lancer, Chaos Knight, 
Arc Warden
Phoenix
* Phoenix's limit AoE, damage-over-time abilities give Io plenty of time to save allies with Relocate.
Chaos Knight
* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, 
Lycan, Naga Siren, 
Nature's Prophet, Phantom Lancer, 
Shadow Shaman, Terrorblade, 
Visage, 
Warlock, Wraith King.
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.
Phoenix
* Heroes with slow movement speeds and small health pools (supports like Crystal Maiden or 
Witch Doctor) are easy targets for Phoenix. Should they be inflicted by its DOT debuffs, they will be very quickly killed without even getting a chance to fight back.
Phoenix
* Inner Beast helps Beastmaster's team destroy Supernova quickly.
Chaos Knight
* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, 
Bloodseeker, 
Clockwerk, 
Doom, Shadow Shaman.
Chaos Knight
* Quill Spray quickly destroys Chaos Knight's Phantasms.
Phoenix
* Heroes with high health especially Strength heroes will take more damage on Sun Ray: Axe, 
Pudge, 
Bristleback, 
Mars.
Chaos Knight
* Faceless Void's lack of strong area-of-effect spells makes it difficult for him to fight against Chaos Knight and his Phantasms.
* From a safe distance and if not caught, Chaos Knight can use Reality Rift to pull Faceless Void out of the 
Chronosphere which combined with Chaos Bolt can expose him to being bursted down by Chaos Knight's team before Void even succeeds to escape with 
Time Walk.
Phoenix
* Fire Spirits does damage over time, preventing Faceless Void from backtracking the full damage with Time Walk.
* Fire Spirits applies a big attack speed slow, stopping Faceless Void from doing many attacks while in Chronosphere.
* Sun Ray can heal allies and damage Faceless Void from outside Chronosphere.
* Supernova can be cast outside of Chronosphere, forcing Faceless Void to step away from it, lest he'll take a lot of damage
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.
Phoenix
* Lone druid's bear attacks on Phoenix's Supernova Egg don't increase the hit count. Given that Lone Druid's main hero often doesn't have much farm, the Supernova Egg is less likely to get killed.
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, Beastmaster, Warlock, Wraith King. And even though Chen can convert enemy summons with Holy Persuasion, their much greater numbers will often overwhelm Chen and his creeps.
Phoenix
* Phoenix's large damage over time with Icarus Dive and Fire Spirits can kill Chen's allies before he can use Hand of God.
* Phoenix naturally buys 
Spirit Vessel, which allows him to reduce healing from 
Divine Favor and 
Hand of God.
* Phoenix's Supernova cannot be damaged by Chen's creeps, and their normal speed means they will often not be able to kill Phoenix whenever he uses Supernova.
Additional:
* Not only Phoenix is able to disrupt Chen's jungling with Fire Spirits, but its high damage over time can also force Chen to use Hand of God prematurely, potentially wasting any chance to save his allies during teamfights.
* Creeps' damage and attack speed are very abysmal, so Chen often cannot kill Phoenix whenever it casts Supernova.
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), Jakiro, 
Pugna, Doom
Phoenix
* Her 
Refraction charges can and will be easily burned away by Phoenix's damage over time abilities, and 
Meld can't protect her from Phoenix's AoE abilities, even without detection.
Additional:
* Phoenix's abilities target and deals damage over time, making them a threat against Meld and Refraction. His abilities' nature makes them pretty hard to correctly land on the target, but that is not a problem against a Templar Assassin that needs to stand still during Meld.
* Icarus Dive allows Phoenix to shrug off the slow from her trap and make an easy escape from her ambush.
* As Templar Assassin relies on her quality-over-quantity bursting attacks to make quick work on fragile target, Fire Spirits' attack speed reduction can cripple her ability to deals any damage during combat. With the debuff applied in early-mid game, a Meld-breaking hit from her is significantly slowed to the point that her target can travel a safe distance before she even lands the hit.
* Sun Ray has a quick damage tick and will burn through her Refraction in no time.
* Supernova deals damage over time in an incredibly large area, and again with her quality-over-quantity style, she may not be able to attack quickly enough to break through the Phoenix Sun by herself. (not to mention the debuff from Fire Spirits) This can lead to a failed ganking attempt or even a turnaround.
Chaos Knight
* Chaos Bolt and Reality Rift makes Tiny's low mobility non existent.
* Chaos Strike means Chaos Knight will most likely survive longer in a duel between the two because Tiny has much lower attack speed.
* Chaos Knight has a 3.2 strength growth, making him one of the most tanky heroes and a very difficult target for Tiny to burst.
Phoenix
* Heroes that are able to slow Tiny's attack speed, like 
Tusk and Phoenix, will greatly limit his Physical damage output.
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.
Additional:
* Unlike any other illusion heroes, Chaos Knight is the worst target for Pudge to hook as it will definitely backfire him.
* Phantasm are significantly tankier than most illusion and deal full damage, which will quickly kill Pudge due to his low armor.
* it becomes worse if pudge is affected with Reality Rift, which reduces his already abysmal base armor even lower.
* Low movement speed and low mobility means Pudge will struggle to escape or outrun Chaos Knight in most cases.
Phoenix
* Heroes with high health especially Strength heroes will take more damage on Sun Ray: Axe, Pudge, Bristleback, Mars.
Chaos Knight
* Heroes with summons and illusions as Spirit Breaker has no strong AoE capabilities to deal with them: Chaos Knight, Phantom Lancer, Terrorblade, Naga Siren, Broodmother, Warlock, Visage, Nature's Prophet, Shadow Shaman, Lycan, Wraith King.
Phoenix
* Due to Spirit Breaker's low attack speed, Supernova is problematic for Spirit Breaker to take down, and even more so with Fire Spirits debuff applied.
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 without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.
Phoenix
* Fire Spirits applies a severe attack speed slow, severely hindering Phantom Assassin's damage output.
* Phantom Assassin cannot cast Phantom Strike on Phoenix during Supernova.
Additional:
* While her 
Phantom Strike does give limited extra attack speed, she cannot use the ability against the Phoenix Sun, and while her 
Blur may protect her from attacks, Phoenix's strong magical DPS burns away her small health pool quickly, and the attack speed slow makes her unable to fight back (provided she has no source of spell immunity).
Chaos Knight
* 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.
Phoenix
* Phoenix with Supernova
* 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
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.
Phoenix
* Icarus Dive quickly escapes from Shadow Demon abilities, especially 
Demonic Purge.
* Phoenix AoE abilities remove Shadow Demon's illusions created by 
Disruption.
Chaos Knight
* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.
Phoenix
* Clockwerk being confined in his own Power Cogs means Clockwerk is unable to quickly escape from Phoenix's Sun Ray and Supernova.
* Sun Ray will also heal the enemy Clockwerk is fighting, making it unlikely for Clockwerk to take an enemy down with him.
* For the same reasons, Phoenix also makes a powerful ally for Clockwerk when the situation is reversed.
Chaos Knight
* Heroes that can overwhelm Visage by sheer number like Chaos Knight, Meepo, Terrorblade and Phantom Lancer.
Phoenix
* Phoenix's Supernova cannot be damaged by Familiars.
* In the early and mid game, Sun Ray won't deal enough damage to be reduced by Gravekeeper's Cloak.
* Once Sun Ray deals enough damage to protect Visage, a layer of Gravekeeper's Cloak is burnt every 0.2 seconds.
Chaos Knight
* Innately fragile heroes will die almost instantly to Reality Rift while Chaos Knight has illusions active: Drow Ranger, Bane, Necrophos, Crystal Maiden.
Additional:
* Reality Rift will disable Drow Ranger's Marksmanship, along with Chaos Bolt he can keep her locked for enough time to be killed.
Phoenix
* Heroes who depend on attacks (such as 
Shadow Fiend or Drow Ranger) can be nullified by Fire Spirits' attack speed slow.
Chaos Knight
* Sniper is very fragile and has low movement speed, making an exceptionally easy target for Chaos Knight to initiate on.
* Sniper has no innate ability to deal with Phantasm or escape a Reality Rift and Chaos Bolt combo.
* In most cases, Sniper likes to stay far in the backline to deal damage, thus he is vulnerable if Chaos Knight manages to jump on him in the back line, which will usually spell a quick end for Sniper.
Chaos Knight
* Razor has no way to deal with Chaos Knight's multiple illusions from Phantasm.
Phoenix
* Fire Spirits greatly reduces Slardar's already low starting attack speed (which Bash of the Deep relies on), making the laning phase very hard for him and discouraging Slardar from aggressively threatening lane kills.
* Supernova, ignoring Phoenix's lack of armor and Slardar's high damage single hits, is extremely hard for Slardar to take down on his own, especially after being hit by Fire Spirits.
* Icarus Dive is one of the longest distance escape spells in the game, and can help a good Phoenix escape from Slardar before he gets a Blink Dagger. However, the high cooldown means Phoenix is vulnerable to backstabs from any roamers after said spell is used.
* Slardar can interrupt an Icarus Dive from completing the flight with both of his stuns, however, likely leading to death if Supernova is on cooldown.
* A lot of the items a Phoenix builds throughout the game naturally counter Slardar. 
Shiva's Guard, 
Heaven's Halberd and 
Eul's Scepter of Divinity all stall Slardar's normal attacks in some way, while Spirit Vessel's percentage-based damage is good against his innate durability.
Chaos Knight
* Life Drain does not instantly kill the illusions from Phantasm
* Chaos Bolt and Reality Rift can easily interrupt the channeling from Life Drain.
* Reality Rift makes it harder for Pugna to keep his distance between Chaos Knight.
* Nether Ward barely deals any significant damage on Chaos Knight as Chaos Knight's abilities do not cost a lot of mana
* The overwhelming damage of Chaos Knight and his illusions will do a quick work on Pugna's poor HP pool, or safely remove the Nether Ward from the battlefield.
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.
Chaos Knight
* Phantasm dispels Ignite and makes targeting the real Chaos Knight much harder.
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.
Chaos Knight
* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.
Chaos Knight
* Heroes with abilities that can close the gap can easily kill Muerta: 
Storm Spirit, 
Earth Spirit, Ember Spirit, 
Void Spirit, Lycan, Chaos Knight, Tusk.
Chaos Knight
* Unlike with other heroes who can summon illusions of themselves, Terrorblade's illusions from 
Conjure Image have different colors than other illusions which can be seen even by enemy team, which can also make Terrorblade weak even against heroes he naturally counters: Bane, Lifestealer, 
Spectre, Chaos Knight, 
Spirit Breaker, 
Sniper. Terrorblade's only solution to counter this problem is to get Manta Style as quickly as possible.
Phoenix
* Heroes with high health especially Strength heroes will take more damage on Sun Ray: Axe, Pudge, Bristleback, Mars.
Chaos Knight
* Heroes the make heavy use of illusions, like Chaos Knight, Phantom Lancer, Terrorblade, 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.
Phoenix
* Heroes with slow movement speeds and small health pools (supports like Crystal Maiden or Witch Doctor) are easy targets for Phoenix. Should they be inflicted by its DOT debuffs, they will be very quickly killed without even getting a chance to fight back.
Phoenix
* Heroes who depend on attacks (such as Shadow Fiend or Drow Ranger) can be nullified by Fire Spirits' attack speed slow.
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.
Phoenix
* Heroes that depend on disrupting fights with ability combos or big ultimate abilities are vulnerable to the long stun of Fiend's Grip: 
Disruptor, Death Prophet, Enigma, 
Faceless Void, 
Invoker, Lich, Magnus, Mars, 
Medusa, 
Outworld Destroyer, Phoenix, Puck, Queen of Pain, Shadow Fiend, 
Treant Protector, 
Underlord, 
Winter Wyvern, Witch Doctor, 
Zeus.
Chaos Knight
* Heroes with illusions and summons can swarm and overwhelm Bane, who has no area abilities to deal with them outside from Aghanim's Shard upgraded 
Brain Sap: Broodmother, Chaos Knight, Naga Siren, Nature's Prophet, Phantom Lancer, Terrorblade, Visage, Warlock, Wraith King.
Additional:
* Phantasm's illusions make it difficult for Bane to target Chaos Knight with 
Nightmare, 
Enfeeble, and 
Fiend's Grip.
* Chaos Bolt is a comparatively low cooldown tool to interrupt Fiend's Grip.
* Nightmare can be transferred by Phantasm illusions.
Phoenix
* Heroes with hiding abilities can protect disabled allies: Outworld Destroyer, 
Shadow Demon, Tusk, Phoenix with Aghanim's Scepter.
Chaos Knight
* Phantasm gives Chaos Knight a significant advantage against single-target damage dealers: Lifestealer, Wraith King, 
Night Stalker, Troll Warlord.
Additional:
* 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
* 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 his allies and deal with him, preventing him from doing his job. Such heroes include Chaos Knight, Spirit Breaker, Riki, and more.
Chaos Knight
* Single-target disablers will have difficulty locking down a Chaos Knight with Phantasm active: Bane, Beastmaster, Bloodseeker, Clockwerk, Doom, Shadow Shaman.
Chaos Knight
* Heroes who relies on illusions and summons (Beastmaster, Chaos Knight, etc.).
Phoenix
* Heroes with blink or movement abilities, which are disabled by Pounce's leash: 
Anti-Mage, Earth Spirit, Faceless Void, Magnus, 
Mirana, 
Monkey King, 
Morphling, 
Pangolier, Phantom Assassin, Phoenix, Puck, Queen of Pain, Riki, Sand King, Spirit Breaker, 
Timbersaw, Tusk.
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.
Chaos Knight
* Illusion heroes will struggle against Primal Beast's area damage capability, such as Chaos Knight, Naga Siren, Terrorblade.
Phoenix
* Primal Beast is disarmed during Trample so will be unable to destroy a Supernova no matter how close it is to him.
* The same ability can also be used to save allies with the help of an Aghanim's Scepter.
* Sun Ray will do thousands of damage to Primal Beast if surviving a full channel time due to his high health scaling for the ability.
* Icarus Dive is a fantastic way to escape Primal Beast after he has used Onslaught.
* Phoenix has a naturally very high health pool making it hard for Primal Beast to deal with him with his magical damage.
Chaos Knight
* Heroes with gap-closing abilities will be easy targets for Berserker's Call: Phantom Assassin, Faceless Void, Slark, Chaos Knight, Morphling, Queen of Pain
Additional:
* 
Berserker's Call allows Axe to lock down Chaos Knight and his illusions even through Black King Bar.
* 
Counter Helix combined with 
Blade Mail clears illusions out in no time.
Phoenix
* Sun Ray allows Phoenix to heal any allies caught in Berserker's Call while burning away Axe's high HP at the same time.
* Icarus Dive and Fire Spirits puts Axe's Blink Dagger on cooldown.
* Axe's slow attack speed makes it difficult for him to destroy Supernova on his own.
Phoenix
* Since all of Phoenix's abilities (except for Supernova) have health costs, heroes like 
Ancient Apparition or Necrophos can turn Phoenix's abilities against it. However, Supernova does completely protect Phoenix from 
Ice Blast.
Phoenix
* 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.
Additional:
* Supernova with or without Aghanim's Scepter allows to save ally or himself through Ice Blast.
* Icarus Dive quickly escapes from 
Cold Feet.
Phoenix
* Heroes with spell immunity-granting spells will render Phoenix useless against them, as Phoenix has almost no spell immunity-piercing ability, other than the stun at the end of Supernova: Lifestealer, Juggernaut.
Chaos Knight
* Level 20 talent allows Reality Rift to bypass spell immunity provided by 
Rage, thus negating the advantage Lifestealer has in his kit.
* The fact that Lifestealer lacks wave clearing and reliable lockdown makes it difficult to fight Chaos Knight's illusions.
* 
Feast is largely negated by Chaos Knight's high burst damage from Chaos Strike.
Additional:
* Chaos Strike is a strong burst damage passive that allows Chaos Knight to stand up and even survive Lifestealer's attacks. Level 20 Talent: Reality Rift Pierces Spell Immunity allows him to burst down Lifestealer even while he is in Rage.
* Lifestealer's single-target nature will struggle against Chaos Knight's Phantasm illusions and will be forced to itemize for them.
Phoenix
* 
Void can interrupt Icarus Dive.
* His 
Crippling Fear's silence will shutdown a spell caster Phoenix.
* However, Phoenix punishes Night Stalker with Supernova because it will turn night into day, and it has a higher priority than 
Dark Ascension, effectively canceling the passive bonuses Night Stalker gets from 
Hunter in the Night.
Chaos Knight
* Phantasm gives Chaos Knight a significant advantage against single-target damage dealers: Lifestealer, Wraith King, Night Stalker, Troll Warlord.
Additional:
* Chaos Bolt can stun Night Stalker outside of Crippling Fears relatively small radius.
* Reality Rift is a great way to force Night Stalker to fight Chaos Knight, a hero with massive health and damage output. It also forces Night Stalker's Crippling Fear off his primary target.
* Night Stalker doesn't have a lot of ways to deal with multiple targets, which makes him vulnerable to Phantasm illusions unless Night Stalker buys Aghanim's Scepter.
Phoenix
* Phoenix turns night to day, overriding Dark Ascension during Supernova.
Chaos Knight
* 
Juxtapose allows Phantom Lancer to overwhelm Chaos Knight due to his single-target abilities.
* Phantom Lancer often builds a Manta Style, which can be used to disjoint Chaos Bolt or dispel Reality Rift.
* Doppelganger can be used to dodge Chaos Bolt.
* 
Diffusal Blade, another common item on Phantom Lancer, can quickly drain Chaos Knight's low mana pool, leaving him unable to cast spells.
Additional:
* 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.
Phoenix
* Phoenix's AoE abilities can prove troublesome for Phantom Lancer.
* Fire Spirits dramatically reduces Phantom Lancer and his illusions' attack speed.
* Icarus Dive's movement speed reduction makes retreating difficult.
* Supernova burns away illusions, and is invulnerable to attacks from illusions.
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.
Phoenix
* Icarus Dive and Supernova can destroy the tree Monkey King is standing on.
* Fire Spirits reduces Monkey King's attack speed, preventing Monkey King from building up Jingu Mastery.
* Supernova can be casted next to Wukong's Command, forcing Monkey King to step away of it or to withstand its massive AOE damage
Additional:
* Icarus Dive, Sun Ray, and Supernova all destroy trees that Monkey King relies on to use his ability 
Tree Dance. If you spot him, you can quickly Icarus Dive in his direction and then follow up with Fire Spirits and Supernova. If you manage to cut the tree he is on, he will be stunned for 4 seconds and will be forced to take a lot of damage. However, most Monkey King players tend to build attack speed items to make use of their passive, Jingu Mastery, so a battle against a farmed Monkey King will depend on who gets the jump on the other first.
Phoenix
* Any hero with high attack speed will be a threat to Phoenix when it initiates, as they can easily tear down a Supernova, perhaps even while debuffed by Fire Spirits: Juggernaut, Clinkz, Troll Warlord, Beastmaster, Lina.
Additional:
* Due to Fervor and Battle Trance, Troll Warlord is one of the best heroes to deal with Supernova.
Chaos Knight
* Phantasm gives Chaos Knight a significant advantage against single-target damage dealers: Lifestealer, Wraith King, Night Stalker, Troll Warlord.
Additional:
* 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.
Chaos Knight
* 
Echo Slam will deal a colossal amount of damage to your Phantasms, as will 
Fissure at lower levels.
* The area stuns from 
Aftershock will always stun Chaos Knight's illusions, since they can't use Black King Bar.
* However, Earthshaker should not attempt to fight a farmed Chaos Knight, since he will be completely obliterated by Chaos Knight's colossal damage output, even if he managed to land an Echo Slam
Additional:
* Echo Slam's damage potential increases due to Chaos Knight's Phantasm illusions.
Phoenix
* Supernova allows Phoenix to save himself (or an ally, with Aghanim's Scepter) through Echo Slam. Earthshaker will also have a difficult time destroying the supernova, due to his low base attack time and poor agility.
* Icarus Dive can pass through Earthshaker's Fissure.
* Most of Phoenix's abilities disable Earthshaker's Blink Dagger for a good period of time due to the damage-over-time nature of its spells.
Phoenix
* Silence (and mana burns) will be a persistent problem for Phoenix, as it is heavily reliant on its abilities whether defensively or offensively, so heroes like Death Prophet, Skywrath Mage, and even Nyx Assassin must be closely observed to prevent being shut down by these heroes.
* Hexes are a greater threat to Phoenix as they also disable items, preventing Phoenix from dispelling the debuff on its own.
Chaos Knight
* Skywrath Mage also has a terrible time fighting against anything that isn't a hero. 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.
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.
Phoenix
* Phoenix will usually be on the sidelines or further back ready to use Sun Ray. Even after Magnus successfully uses Reverse Polarity and skewer Phoenix's teammates, Phoenix can usually counter-initiate using all of its abilities.
Phoenix
* Huskar's high attack speed can counteract Fire Spirits, and easily destroy the Supernova.
Additional:
* 
Berserker's Blood will let Huskar easily face down a Supernova with increased attack speed.
* Icarus Dive may not be an easy escape from Huskar either as he can chase Phoenix during it with 
Life Break if Huskar times it right.
* However, Phoenix can buy items which can
Chaos Knight
* Huskar's low armor and movement speed make an easy target for Chaos Knight to initiate on with Reality Rift and Chaos Bolt.
* Other than 
Inner Fire, Huskar has no reliable area of effect ability to clear Phantasm illusions.
* Huskar likes to stay at low health to benefit from his Berserker's Blood, thus making him vulnerable to Chaos Knight's high burst physical damage.
Additional:
* Chaos Bolt can stun Huskar when he jump in with Life break, giving 4 seconds maximum for Chaos Knight to deliver a beatdown.
* Reality Rift further reduces Huskar's low armor, boosting Chaos Knight's damage even more.
* Berserker's Blood offer no protection against Chaos Strike, which deal physical damage.
* Phantasm can be used to dispel the disarm from Inner Fire.
* Although Huskar can use this to disarm the illusion instead, buying himself some times.
Phoenix
* Ursa can easily unleash a number of attacks in an incredibly short amount of time, easily destroying the Supernova in a couple of seconds regardless of Fire Spirits' debuff. His 
Enrage also dampens any damage Phoenix might toss at his direction, as well as remove any debuffs Phoenix may place on him.
Chaos Knight
* 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.
Additional:
* Ursa has no way to clear illusions quickly, making him vulnerable to Chaos bolt and Phantasm combo.
* Reality Rift can quickly relocate or reinitiate on Ursa once the duration of Enrage is over.
* Phantasm can be used to dispel Earthshock's slow. Manta Style is another item that counter Ursa greatly.
* Ursa has low mobility, once jumped on by Reality Rift, Ursa struggles to escape.
Phoenix
* Juggernaut's high attack speed lets him destroy a Supernova easily. He can even attack a Supernova during Blade Fury with his regular attacks.
* 
Blade Fury protects Juggernaut from all of Phoenix's spells (except Supernova, which pierces spell immunity).
* Blade Fury can also dispel the attack speed slow from Fire Spirits and the movement speed slow from Icarus Dive.
* Phoenix's Icarus Dive will not protect it from Omnislash unless it dives into creeps, and Phoenix's low armor makes for an easy kill.
Chaos Knight
* While Blade Fury is on cooldown, Juggernaut can be easily killed by a standard Chaos Bolt & Reality Rift combo.
* Phantasm illusions can tank Omnislash.
Chaos Knight
* Sand King's massive area damage output, particularly 
Epicenter, allows him to quickly take down Chaos Knight and his illusions.
* Sand King can also apply 
Caustic Finale to illusions with attacks for extra damage when they die.
Phoenix
* Sand King has nothing to deal with Supernova, as none of his spells are effective.
* The damage-over-time abilities of Phoenix disable Sand King's Blink Dagger very often.
Phoenix
* Tempest Double, Magnetic Field's attack speed bonus, and Arc Warden's high attack range will easily destroy a Phoenix using Supernova much faster than usual.
* Phoenix is very weak against pushers, especially those like Arc Warden who can kill him easily, as his skillset works best in teamfights.
Additional:
* His 
Tempest Double is not an illusion, but rather a full hero unit, which effectively reduces half of the Supernova's health. His 
Magnetic Field can tremendously boost his attack speed, allowing him to destroy Supernova in no time even when he's affected by Fire Spirits.
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 will struggle to escape due to low mobility and lack of stun.
Chaos Knight
* Tidebringer, Torrent and Ghostship destroys Chaos Knight's Phantasm army all through the game.
Phoenix
* Supernova negates Kunkka's combo entirely, as it can't be affected by spells while using Supernova.
* Icarus Dive also allows Phoenix to dodge Ghostship and Torrent.
Chaos Knight
* Illusions and summons are double-edge sword type of matchup for Luna. On one hand, they can tank damage from Eclipse, but on the other hand, she can easily clear them before Eclipse with Moon Glaives. Examples include 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, Meepo and Arc Warden).
Chaos Knight
* Heroes that create illusions: 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, 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, but that will require lots of farming for right-click items.
Chaos Knight
* Heroes with strong area damage to destroy Phantasm illusions: Axe, Ember Spirit, Legion Commander, Phoenix
Phoenix
* Heroes who can hide the Dueled target (Outworld Destroyer, Shadow Demon, Tusk, Phoenix with Aghanim's Scepter etc).
Additional:
* Legion Commander relies on her powerful attack and her 
Duel to be effective. But if Phoenix gets the jump on her first, she can find herself severely slowed, taking heavy damage, and find herself unable to Duel a burning Supernova.
* It must be noted that 
Press the Attack will both dispel the attack slow of Fire Spirits and grant her or whoever she targets bonus attack speed. This allows her to easily destroy a Supernova if caution is not taken to prevent this from occurring. As such, it would be a better decision to simply avoid a farmed or skilled Legion Commander instead of attempting to overpower her.
* If an ally is caught by Duel, Phoenix can use Sun Ray to heal the ally and damage Legion Commander, possibly swinging the Duel in their team's favor. Or with Aghanim's Scepter, Phoenix can save an ally from dying in Duel with Supernova and cancel the Duel as well.
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.
*
Phoenix
* Although Phoenix has many ways to disable a Blink Dagger, the high cooldown of all of its spells makes them not as reliable for this. Also, its spells cost a lot of health to use, making it easy to get nuked down.
Supernova to refresh itself, giving Puck's team time to finish it off, or allow Puck to burst Phoenix down.
Icarus Dive without consequences. Waning Rift and Dream Coil are also able to cancel 
Sun Ray, which is its main source of damage in the late game.
* Waning Rift prevents Phoenix from using
* Dream Coil prevents Phoenix from using