* Heartstopper Aura is effective against high health heroes, and Pudge is no exception. Coupled with his constant self-damage from Rot, being around Necrophos could prove risky for an overconfident Pudge.
* Regardless of how much health Pudge gains through Flesh Heap, Reaper's Scythe will often kill Pudge should his health fall below 40%, making Necrophos an ideal counter versus Pudge.
Additional:
* No matter how high Pudge builds up strength with his Flesh Heap, all it needs is for him to fall below a certain percentage of health for him to fall to Reaper's Scythe. Considering his constant self-damage with Rot, being around Heartstopper Aura will prove risky for an overconfident Pudge.

* 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.

* 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.

* Ghost Shroud can be use both offensively to slow Lone Druid or Defensively to prevent Lone Druid and The Spirit Bear from attacking him.
* Heartstopper aura burns the Spirit bear High HP over time. Additionally, it can deal decent damage to Lone Druid during his True Form.

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

* Necrophos usually doesn't build much attack damage to steal from.
* He can use Ghost Shroud to prevent Razor from attacking him with the stolen damage from Static Link.
* Razor is somewhat vulnerable to magical damage, and Reaper's Scythe prevents him from escaping with his high movement speed when things get dangerous.

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

* Due to Doom's naturally high health, strength gain and common itemization for durability, Heartstopper Aura is particularly effective. The health loss is also large enough that, throughout all stages of the game, the aura effectively neuters the health regeneration granted by Devour.
* Necrophos can help to keep both himself and his allies alive during Doom through his natural regeneration granted by Heartstopper Aura (which is not disabled by Doom), or in the case of an ally, through his Death Pulse. Additionally, Necrophos is an ideal Mekansm carrier. Should one be bought, kills against Necrophos' team can be difficult to secure due to the damage-over-time nature of Doom and his abilities.
* Doom typically wants to be a hero that soaks attention from the enemy team and takes the role of an initiator and disabler. As such, Doom is an ideal target for Reaper's Scythe, as it is likely Doom will be at the fore-front of any fight.

* Because Huskar tends to stay at low health to gain the maximum bonuses from Berserker's Blood, it makes him an exceptionally prime target for Reaper's Scythe.
Additional:
* Huskar is often at low health, making him easy prey for Reaper's Scythe.
* Ghost Shroud prevents Huskar from stacking Burning Spear, and if Heartstopper Aura stacks are active, can regenerate health lost to existing stacks.

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

* Heartstopper Aura can do a decent damage overtime to Chen's High-Health-Creep Army, and Chen does not have any source of burst damage to Necrophos.
* Necrophos can purchase a Spirit Vessel to provide an AOE debuff that reduce the healing from Divine Favor and Hand of God.

* 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.

* Necrophos is a dangerous opponent to go against with. Regardless of how many strength Undying has gained from Decay, Necrophos can finish off Undying with Reaper's Scythe once Undying's HP falls below a certain threshold.
* Heartstopper Aura will do more damage to Undying if he gained strength from Decay, as it does damage based on a hero's maximum health.

* 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.

* 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.

* Heroes with magical burst damage can often kill Phantom Assassin before she gets to do much: Necrophos, Nyx Assassin, Gyrocopter.

* 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 have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include Crystal Maiden, Witch Doctor, Warlock or Shadow Fiend.

* Heroes with area heals prevents Bloodseeker from bringing enemies low, and therefore deny him his Thirst bonuses and health return: Necrophos, Dazzle

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

* 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.

* Reaper's Scythe will turn Tiny's high health against him.
* Heartstopper Aura does substantial damage to Tiny as a result of his high max health.

* 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.

* Necrophos' largely magical damage completely ignores Bulwark.
* Ghost Shroud protects Necrophos from God's Rebuke but more importantly stops Mars from being a threat in lane.

* 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!.

* Reaper's Scythe can kill Alchemist before Chemical Rage has the time to heal him.
* Ghost Shroud can prevent Alchemist from attacking Necrophos, as well as make him immune to Acid Spray and Unstable Concoction damage.
* Heartstopper Aura will do damage as long as Necrophos is alive based on health percentage, which is a problem for a strength hero such as Alchemist.

* 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.

* Reaper's Scythe can kill Terrorblade quickly before he has chance to use Sunder.
* Ghost Shroud protects Necrophos against Terrorblade's high attack damage.

* 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 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.

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

* 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.

* 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.

* Reaper's Scythe and Heartstopper Aura deal percentage-based damage, ignoring Underlord's high health.

* Necrophos's Reaper's Scythe can finish off a low-health Morphling.

* Heroes who rely on physical damage are easily negated by Ghost Shroud: Phantom Assassin, Wraith King, Juggernaut.

* 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.

* Heroes that have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include Crystal Maiden, Witch Doctor, Warlock or Shadow Fiend.

* 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.

* Heroes that have escape abilities (such as Queen of Pain, Storm Spirit or Timbersaw) can be either nullified by Reaper's Scythe or a complimentary item for Necrophos (like Rod of Atos or Scythe of Vyse). If Necrophos is quick enough and enters range, they can quickly, if not instantly, die if they are not quick enough.

* Heroes that have escape abilities (such as Queen of Pain, Storm Spirit or Timbersaw) can be either nullified by Reaper's Scythe or a complimentary item for Necrophos (like Rod of Atos or Scythe of Vyse). If Necrophos is quick enough and enters range, they can quickly, if not instantly, die if they are not quick enough.

* 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

* 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.

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

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

* Heroes who rely on physical damage are easily negated by Ghost Shroud: Phantom Assassin, Wraith King, Juggernaut.

* Heroes that have small health pools and little to no escape mechanisms are even easier prey for Necrophos. Ghost Shroud's slow will allow him to catch him with them, and get nuked down with his abilities, even preventing retaliation due to Reaper's Scythe's stun. Such heroes include Crystal Maiden, Witch Doctor, Warlock or Shadow Fiend.

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

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

* 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.).

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

* With high health and rarely buying Linken's Sphere or Black King Bar, Centaur Warrunner is a good target for Reaper's Scythe. However, Centaur Warrunner can resolve this problem by buying Pipe of Insight or Hood of Defiance to diminish its damage.
* Heartstopper Aura will do well against high health heroes such as Centaur Warrunner.

* 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.
Additional:
* 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.

* Death Pulse can single out Spectre from her illusions, as well as heal his team against her. He also usually stands close to his allies for Death Pulse, effectively disabling Desolate.

* Death Pulse can easily wipe out Broodmother's spiderlings if they're too close while also offering Necrophos a source of regeneration for Broodmother's harass in lane.
* Ghost Shroud prevents Broodmother or her spiderlings from damaging Necrophos temporarily.
* Heartstopper Aura will regenerate lost health and mana for every spiderling or spiderite Necrophos manages to kill.

* A couple of long-range heroes with excellent laning like Mirana, Lina, Necrophos, Death Prophet. The key to success is sticking together and attacking Luna whenever she enters the range, without even giving Luna a chance to retaliate. Multiple long-range heroes is a reason to pick another hero.

* 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).

* 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.

* 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.

* Heartstopper Aura effectively negates Timbersaw's large HP pool as well as HP regen.
* Death Pulse together with health and mana regeneration from killed creeps helps Necrophos and his teammates survive Timbersaw's burst damage.
* As a tanky hero that stays in the middle of teamfights, Timbersaw is an easy target for Reaper's Scythe.

* 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.

* Frequent healing from Death Pulse and Mekansm makes it difficult for Axe to finish off targets with Culling Blade.
* Ghost Shroud's instant cast time allows Necrophos to turn ethereal before being initiated on by Berserker's Call. This prevents him from attacking Axe while taunted, thus lowering the chance to proc Counter Helix.
* Axe's high health is relatively ineffective against Heartstopper Aura's percentage-based health degeneration.
* Reaper's Scythe negates Axe's tankiness, and can kill him quickly after initiation.
Additional:
* Frequent healing from Death Pulse makes it difficult for Axe to finish off targets with Culling Blade.
* Reaper's Scythe negates Axe's tankiness, and can kill him quickly after initiation.
* Heartstopper Aura is effective due to Axe's high strength gain.

* Frequent healing from Death Pulse and Mekansm/Guardian Greaves or Pipe of Insight makes it difficult for Earthshaker to execute his combo with Echo Slam.
* Necrophos usually buys Radiance to improve their burning aura damage from Heartstopper Aura will usually disable Earthshaker's Blink Dagger prior to a teamfight, preventing him from initiating or re-initiating.
* Reaper's Scythe allows to kill  Earthshaker while he blinks in, preventing him from executing his combo (although Earthshaker is rarely a primary target).

* 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.

* 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.

* No matter how Tidehunter builds tanky items such as (Guardian Greaves, Crimson Guard or Pipe of Insight), all it needs is for him to fall below a certain percentage of health for him to fall to Reaper's Scythe.

* 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.