Nyx Assassin
* Heroes that have a weak laning stage: 
Spectre, 
Nyx Assassin, 
Clockwerk, 
Spirit Breaker, 
Omniknight, 
Pudge.
Keeper of the Light
* 
Crippling Fear prevents Keeper of the Light from using his spells to keep his team alive during team-fights.
* 
Dark Ascension is very strong against Keeper of the Light, as it allows Night Stalker to jump the backline and quickly kill the squishy Ezalor, especially when combined with the slow from 
Void.
Additional:
* Keeper of the Light's 
Aghanim's Scepter upgrade loses much of its power, due to Night Stalker being able to reduce the duration of daytime by a lot.
Nyx Assassin
* Heroes with invisibility will be detected by Thirst when they have low enough health: 
Bounty Hunter, 
Templar Assassin, 
Riki, 
Clinkz, 
Weaver, 
Treant Protector, Nyx Assassin.
Additional:
* While Burrowing, Nyx is an easy target for a 
Blood Rite, and his only way to counter it is a well-timed 
Spiked Carapace.
* 
Thirst is always a threat to Nyx Assassin, hindering his attempt of escape using 
Vendetta and rendering him unable to surprise Bloodseeker's allies.
* 
Rupture also prevents Nyx Assassin from escaping with Vendetta, as it forces him to stay still.
Keeper of the Light
* Blood Rite makes Ezalor chose between getting off Illuminate or getting silenced for a while, as Illuminate is a channeled ability.
* Blood Rite's silence can completely take Ezalor out of a teamfight, as he relies on his abilities to be useful.
* Keeper of the Light's only mobility source, his high movement speed (via his high base movement speed and through spirit form), is entirely countered by Rupture.
Nyx Assassin
* A well-timed 
Doom prevents Nyx Assassin escaping with Vendetta and fighting back with Spiked Carapace.
* Doom's high health also allows him to easily shrug off Nyx Assassin's burst damage and fend him off.
Keeper of the Light
* Heroes with silences: 
Puck, 
Doom, Riki.
Nyx Assassin
* Duel's long duration prevents Nyx Assassin escaping from Vendetta. With Aghanim's Scepter, she can also bypass Spiked Carapace.
Keeper of the Light
* 
Press the Attack can dispel Blinding Light or Solar Bind from a hero.
* 
Duel can be used to instantly take Keeper of the Light out of a team-fight.
Keeper of the Light
* Heroes with abilities that blind or cause Legion Commander to miss will prevent her from winning Duels: 
Arc Warden, 
Keeper of the Light, Riki, 
Tinker
Nyx Assassin
* 
Blade Fury makes Juggernaut immune to all Nyx's abilities, except Vendetta.
* 
Omnislash. and 
Swiftslash can burst Nyx down, ignoring Spiked Carapace. However, Vendetta can be used to escape, canceling Omnislash/Swiftslash.
Additional:
* Juggernaut's entire skillset greatly counters Nyx Assassin's Spiked Carapace, his most important ability.
* Blade Fury allows Juggernaut to freely attack Nyx Assassin, and deal heavy damage to Nyx Assassin. Nyx Assassin cannot counter Blade Fury with Spiked Carapace because Blade Fury gives Juggernaut spell immunity. And besides Vendetta, Nyx Assassin has no other way of dealing damage to Juggernaut while he is spell immune.
* 
Healing Ward allows Juggernaut to recover himself and his allies from Nyx Assassin's damage output.
* Omnislash and Swiftslash from Aghanim's Scepter can quickly finish off Nyx Assassin. And just like Blade Fury, Nyx Assassin cannot counter neither Omnislash and Swiftslash from Aghanim's Scepter with Spiked Carapace because both abilities render Juggernaut invulnerable. And if Nyx Assassin has no Vendetta available to use for escaping, both abilities will kill him very quickly before he can do anything.
* Overall, any attempt for Nyx Assassin to gank and kill Juggernaut will hurt Nyx Assassin more than Juggernaut.
Keeper of the Light
* Juggernaut's Healing Ward keeps his team healthy even when pushing against Keeper of the Light's 
Illuminate.
* Blade Fury can dispel 
Blinding Light, as well as dodge an incoming Illuminate. Juggernaut can attack towers during Blade Fury, so he can dodge an Illuminate without having to stop pushing.
* Should Keeper of the Light obtain 
Will-o-Wisp through purchasing an Aghanim's Scepter, Juggernaut can make quick work of Ignis Fatuus without being interrupted by its pull.
* Keeper of the Light has low health, low armor, and no natural defense against Blade Fury.
Additional:
* Blade Fury allows him to be immune to all of Ezalor's abilities.
* Healing Ward heals his entire team, mitigating Ezalor's weak magical burst damage.
Keeper of the Light
* Keeper of the Light's Blinding Light makes Juggernaut miss his attacks. However, it can be dispelled easily with Blade Fury.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: 
Jakiro, 
Viper, 
Venomancer, 
Huskar, 
Ember Spirit, 
Dark Seer, 
Sand King, Doom, 
Dawnbreaker. However, this also means they are easily stunned.
Keeper of the Light
* Heroes with hastes: Dark Seer, 
Lycan
Nyx Assassin
* Heroes who build 
Black King Bar as either core or situational item will be able to fight back against Nyx Assassin and freely attack him as Spiked Carapace cannot pierce spell immunity at all: 
Axe, 
Broodmother, Dawnbreaker, 
Enigma, Huskar, Jakiro, 
Legion Commander, 
Lina, 
Luna, Lycan, 
Slardar, 
Slark, 
Troll Warlord, 
Witch Doctor.
Keeper of the Light
* Heroes with channeling abilities: Enigma, Witch Doctor, 
Crystal Maiden.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Jakiro, Viper, Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.
Keeper of the Light
* Jakiro's reliance on his abilities can cause struggles for heroes who rely on evasion or blinds to get upper hand: 
Phantom Assassin, 
Windranger, Riki, Troll Warlord, Keeper of the Light.
Nyx Assassin
* Nyx Assassin's skillset is mostly single-targeted, therefore he will have difficulties against heroes with illusions and summons: 
Naga Siren, Broodmother, Lycan, 
Visage, 
Phantom Lancer. And to make things worse, Nyx Asassin is not a common 
Battle Fury, 
Maelstrom, 
Mjollnir, 
Gleipnir or 
Radiance wielder to counter this problem.
Keeper of the Light
* Heroes with dispels: Legion Commander, 
Oracle, Slark, Phantom Lancer
Nyx Assassin
* Even though Visage's Familiars from 
Summon Familiars are fragile and can be killed quickly with Nyx Assassin's high burst damage, they can deal many instances of damage quickly, minimizing the effectiveness of Spiked Carapace.
* 
Gravekeeper's Cloak and tanky item builds make Visage hard for Nyx to kill with his burst damage. 
Aghanim's Shard upgraded Gravekeeper's Cloak also allows Visage to use 
Stone Form to both recover himself and stun Nyx Assassin if he is close enough to Visage.
* Visage's long range on 
Soul Assumption and 
Grave Chill make him hard to escape from, and Soul Assumption's low cooldown outmatches Spiked Carapace.
Nyx Assassin
* Nyx Assassin wants to start ganking as soon as he gets his Vendetta. Keeping him Tracked prevents him from ganking, and thus from doing his job in the game.
* Nyx Assassin has a lot of armor and health regen, making the nuke damage from Shuriken Toss very good against him.
Additional:
* 
Track hinders Nyx Assassin's ganking and escaping attempts with Vendetta, making him an easy kill for gold as well.
* Bounty Hunter can also use Track on Nyx Assassin while he has Spiked Carapace active without getting stunned as Track deals no damage at all before using 
Shuriken Toss.
Nyx Assassin
* A well-timed 
Berserker's Call can expose Nyx Assassin while he is invisible with Vendetta, and prevent him from using Spiked Carapace.
* Axe can use 
Battle Hunger's damage over time to minimialize effects of Spiked Carapace.
* Axe's high health also allows him to easily shrug off Nyx Assassin's burst damage and fend him off. Especially since Axe is a common 
Heart of Tarrasque wielder, which can completely eliminate any chance for Nyx Assassin to kill Axe alone.
* 
Culling Blade can often kill Nyx Assassin as he is very fragile and vulnerable to damage while Spiked Carapace is on cooldown.
Additional:
* A well-timed Berserker's Call can expose Nyx Assassin while he is invisible with Vendetta, and prevent him from using Spiked Carapace.
* Axe can use Battle Hunger's damage over time to minimialize effects of Spiked Carapace.
* Axe's high health also allows him to easily shrug off Nyx Assassin's burst damage and fend him off. Especially since Axe is a common Heart of Tarrasque wielder, which can completely eliminate any chance for Nyx Assassin to kill Axe alone.
* Culling Blade can often kill Nyx Assassin as he is very fragile and vulnerable to damage while Spiked Carapace is on cooldown.
Nyx Assassin
* 
Cyclone from Storm in 
Primal Split can waste Nyx's Spiked Carapace, since its duration is shorter than the Cyclone's.
Nyx Assassin
* Lycan's high health allows him to easily shrug off Nyx Assassin's burst damage and fend him off.
* As Lycan commonly buys Black King Bar, he can use it to freely attack Nyx Assassin and chase after him with 
Shapeshift.
* Lycan can also use his wolves from 
Summon Wolves to attack Nyx Assassin while he has Spiked Carapace active without getting stunned himself.
Keeper of the Light
* Heroes with hastes: Dark Seer, Lycan
Keeper of the Light
* Keeper of the Light has a blind, which causes Lycan to miss his attacks.
Nyx Assassin
* Centaur's low Intelligence makes 
Mind Flare do low damage.
* With some creative skill builds, Centaur's Hoof Stomp stun duration should always last longer than Spiked Carapace stun, so escaping unscathed is hard for Nyx.
* With 
Blink Dagger and detection, Centaur can devastate Nyx in the open.
* However, bear in mind that Nyx can also easily initiate on Centaur Warrunner as well if he uses Spiked Carapace in anticipation, and with Vendetta. The damage from Retaliate will be reflected back to Centaur Warrunner, stunning him with no chance to react after he's revealed himself, and should guarantee a successful 
Impale.
Nyx Assassin
* Even though Nyx Assassin can easily kill Luna with his high burst damage, Luna can also do the same to him if he is not careful.
* 
Lucent Beam can deal a fair amount of damage to Nyx Assassin if he has no Spiked Carapace available to use. Although Luna should be patient using Lucent Beam on Nyx Assassin when he uses Spiked Carapace.
* As Luna commonly buys Black King Bar, she can use it to freely attack Nyx Assassin whenever he tries to defend himself with Spiked Carapace during teamfights. Luna can also buy 
Eye of Skadi and 
Manta Style to survive Nyx Assassin's burst damage and distract him.
* Though Vendetta can deal serious damage to Luna and avoid 
Eclipse, smart Luna will always buy 
Dust of Appearance to provide vision on Nyx Assassin to her and her team.
Additional:
* Even though Nyx Assassin can easily kill Luna with his high burst damage, Luna can also do the same to him if he is not careful.
* Lucent Beam can deal a fair amount of damage to Nyx Assassin if he has no Spiked Carapace available to use. Although Luna should be patient using Lucent Beam on Nyx Assassin when he uses Spiked Carapace.
* As Luna commonly buys Black King Bar, she can use it to freely attack Nyx Assassin whenever he tries to defend himself with Spiked Carapace during teamfights. Luna can also buy Eye of Skadi and Manta Style to survive Nyx Assassin's burst damage and distract him.
* Though Vendetta can deal serious damage to Luna and avoid Eclipse, smart Luna will always buy Dust of Appearance to provide vision on Nyx Assassin to her and her team.
Nyx Assassin
* 
Corrosive Haze hinders Nyx Assassin's ganking attempts with Vendetta, as well as reducing his armor and make him very vulnerable due to his low health pool.
* 
Guardian Sprint allows Slardar to catch up with Nyx Asssassin and finish him off if he has vision over him.
Nyx Assassin
* Heroes who build mana boosting items but have low mana regeneration are especially vulnerable against Mana Break and Mana Void: 
Timbersaw, Slark, 
Shadow Fiend, Clinkz, 
Bristleback Nyx Assassin, 
Magnus
Keeper of the Light
* Being an intelligence caster hero, Ezalor usually has a high mana pool and low health and armor, making him a prime target for 
Mana Void
* Ezalor's Illuminate damage and Solar Bind's magic resistance reduction are greatly reduced thanks to 
Counterspell. Counterspell can also block and reflect Solar Bind if timed properly.
* Anti-Mage usually is not hampered by Solar Bind or Will-O-Wisp thanks to 
Blink.
* However, despite all of this, if Keeper of the Light is played carefully and tops off his team's mana at all times, Anti Mage will not be able to get off a good Mana Void.
* By the same token once Keeper of the Light gets a 
Octarine Core, he can spam Charka Magic to keep his own mana ful
Keeper of the Light
* Keeper of the Light can stall pushes with Illuminate. This makes him strong against pushing heroes: 
Terrorblade Naga siren 
Nature's Prophet and 
Anti-Mage
Nyx Assassin
* Dragon Knight's heavy armor negates Vendetta's burst physical damage. His large HP pool also gives him a good chance of surviving Nyx Assassin's follow-up nuke damage.
Keeper of the Light
* Heroes with dispels: Legion Commander, Oracle, Slark, Phantom Lancer
Keeper of the Light
* Heroes that can jump and kill him: 
Meepo, Clinkz, Templar Assassin
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Jakiro, Viper, Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Jakiro, Viper, Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.
Keeper of the Light
* Vulnerable spellcasters with no escape mechanisms are easy targets for Huskar: 
Lich, Crystal Maiden, 
Silencer, Keeper of the Light, Venomancer, etc.
Nyx Assassin
* Nyx Assassin can reflect Life Break with Spiked Carapace.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Jakiro, Viper, Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.
Keeper of the Light
* With 
Bloodthorn, Clinkz becomes a strong counter to heroes who rely on evasion and blind such as Windranger, Phantom Assassin, Troll Warlord and Keeper of the Light.
Keeper of the Light
* Heroes with silences: Puck, Doom, Riki.
Keeper of the Light
* 
Finger of Death can instantly shred many targets, especially fragile Heroes like Keeper of the Light, 
Ancient Apparition or Bounty Hunter.
Nyx Assassin
* Heroes who build Black King Bar as either core or situational item will be able to fight back against Nyx Assassin and freely attack him as Spiked Carapace cannot pierce spell immunity at all: Axe, Broodmother, Dawnbreaker, Enigma, Huskar, Jakiro, Legion Commander, Lina, Luna, Lycan, Slardar, Slark, Troll Warlord, Witch Doctor.
Keeper of the Light
* Squishy heroes, usually supports, like 
Lion, Ancient Apparition, Keeper of the Light etc can die quickly to Tiny's magic burst.
Nyx Assassin
* Heroes who build Black King Bar as either core or situational item will be able to fight back against Nyx Assassin and freely attack him as Spiked Carapace cannot pierce spell immunity at all: Axe, Broodmother, Dawnbreaker, Enigma, Huskar, Jakiro, Legion Commander, Lina, Luna, Lycan, Slardar, Slark, Troll Warlord, Witch Doctor.
Keeper of the Light
* Heroes with dispels: Legion Commander, Oracle, Slark, Phantom Lancer
Keeper of the Light
* Melee carries during the laning phase: 
Sven, Slark
Keeper of the Light
* Heroes that can jump and kill him: Meepo, Clinkz, Templar Assassin
Nyx Assassin
* Some abilities deals damage from an independent source and not from the hero itself, so Nyx cannot counter them with Spiked Carapace: illusions or summoning units, 
Homing Missile, 
Nimbus, 
Mass Serpent Ward, 
Death Ward and especially 
Techies's mines.
Nyx Assassin
* Impale and Spiked Carapace stun can be instantly dispelled by Aphotic Shield.
* Abaddon can use Borrowed Time and easily heal for the duration of Borrowed Time by Nyx's burst damage.
Nyx Assassin
* Nyx Assassin might not kill Abaddon with his nuke, but a support Abaddon will struggle to protect an ally from him.
Nyx Assassin
* Nyx Assassin deals large amounts of pure damage with Vendetta and magical damage with Impale and Mind Flare, allowing him to ignore Terrorblade's armor and burst his low health pool down before he can use 
Sunder.
* Nyx Assassin commonly buys 
Urn of Shadows, 
Dagon and 
Meteor Hammer which deal magic damage that ignore Terrorblade's armor.
* However, Terrorblade is a natural Eye of Skadi and Black King Bar wielder, and once he gets those items, Nyx Assassin's solo kill potential against Terrorblade will be gone.
Keeper of the Light
* Keeper of the Light can stall pushes with Illuminate. This makes him strong against pushing heroes: Terrorblade Naga siren Nature's Prophet and Anti-Mage
Nyx Assassin
* Vendetta burns a significant amount of mana on hit, and the damage from the ability drains Medusa's mana pool even further.
* Due to the passive nature of Mystic Snake and Split Shot, it can possibly proc Nyx's Spiked Carapace if he's within range of Medusa's abilities and isn't invisible.
* Medusa lacks single target damage, making Nyx with Aghanim's Scepter extremely hard to deal with if Medusa is the team's main damage source.
Additional:
* With her passive 
Split Shot, Medusa can be easily interrupted by Spiked Carapace during combat, especially during her precious 
Stone Gaze.
* Mana Burn quickly destroys 
Mana Shield, especially if Medusa only increases her mana pool by bolstering intelligence (which has the added bonus of increasing Mana Burn's damage).
* Uncontrollable damage from 
Mystic Snake and Split Shot can trigger Spiked Carapace.
* 
Medusa lacks single target damage, making a Burrowed Nyx Assassin hard to kill.
Keeper of the Light
* Heroes with extremely slow movement speed will cripple against Solar Bind: Medusa, Viper
Additional:
* Will-O-Wisp will keep Medusa busy after she got hit by Blinding Light.
Nyx Assassin
* Heroes with either magical, physical or pure damage burst can often kill Chen or his allies before he can use Hand of God: Lina, Luna, Techies, Shadow Fiend, 
Pugna, Nyx Assassin.
Keeper of the Light
* Heroes with summons/illusions/neutral creep armies: 
Beastmaster, 
Chen, Naga Siren
Nyx Assassin
* Heroes with invisibility: (Riki, Clinkz, Nyx Assassin.
Keeper of the Light
* Keeper of the Light can stall pushes with Illuminate. This makes him strong against pushing heroes: Terrorblade Naga siren Nature's Prophet and Anti-Mage
Nyx Assassin
* Many of Nyx Assassin's abilities are good against Windranger.
* Impale is great for stunning Windranger and allowing additional disables to be landed.
* Mind Flare is useful against Windranger's decent intelligence growth.
* Spiked Carapace is easy to use against Powershot.
* Vendetta allows Nyx Assassin to sneak up on and deal massive damage to Windranger without giving Windranger a chance to use Windrun to evade it.
* Nyx Assassin's item build allows him to easily deal with Windranger.
Nyx Assassin
* Nyx can walk into Firefly with Spiked Carapace and stun Batrider if he has no Spell Immunity, even if Batrider is focusing on other enemy hero.
Nyx Assassin
* Vendetta can deal great damage against her. However, it requires an direct attack, so Nyx Assassin may have difficulties applying Vendetta on her.
* Enchantress's lack of mobility makes her a primary target for ganking with Vendetta.
* Mind Flare can deal a great damage against her due to being an Intelligence hero.
* Spiked Carapace can reflect Impetus and stun Enchantress.
Additional:
* Spiked Carapace reflects the damage from 
Impetus.
* Enchantress is a rather squishy hero, making her fall easily to Nyx Assassin's high burst damage.
Nyx Assassin
* Nyx's Spiked Carapace can reflect the damage of 
Sharpshooter, instantly killing hoodwink. Nyx can also use Vendetta to position himself in such a way to screen allies from Sharpshooter and catch Hoodwink by surprise.
Keeper of the Light
* Blinding Light can knock Monkey King outside of his ultimate, Wukong's Command and can blind him.
* Will-O-Wisp will stun Monkey King from Tree Dance by destroying his tree.
Additional:
* Blinding Light can easily push Monkey King out of Wukong's Command, as well as blinding him.
* Monkey King is vulnerable to burst damage, 
Solar Bind makes him more so
* However, Keeper of the Light can be easily ganked by Monkey King during early-mid game stage.
Nyx Assassin
* Spiked Carapace stops Snapfire's 
Mortimer Kisses.
Keeper of the Light
* Illuminate clears Beastmaster's summons and is effective against his push.
Nyx Assassin
* 
Assassinate is easy to reflect with Spiked Carapace for massive damage.
* 
Shrapnel's area damage can set up an easy stun with Spiked Carapace, especially when combined with Vendetta.
* In the early game, Sniper's low health pool and high intelligence makes him easy prey for Nyx Assassin.
Nyx Assassin
* Nyx Assassin's high burst damage, excellent ganking potential and multiple disables pose a threat to Muerta at all stages of the game.
* Mind Flare allows Nyx Assassin to take advantage of Muerta's high intelligence and make a short work of her low health.
* Spiked Carapace and Vendetta allow Nyx to escape or initiate well against Muerta's low mobility.
* As with most retaliation based abilities, Spiked Carapace can easily take advantage of 
Gunslinger's stray shots.
* However, Muerta is a natural Black King Bar wielder. And if she succeeds to activate it before Nyx Assassin can ambush her, he will go down very quickly against Muerta as Spiked Carapace cannot pierce through debuff immunity at all.
Nyx Assassin
* Spiked Carapace allows Nyx to get an easy long-duration stun on Weaver once he uses Shukuchi, and then he can follow up with Impale.
* Vendetta works as a great setup for both Impale and Spiked Carapace and can deal decent damage to Weaver. Additionally he can neutralize The Swarm beetles due to his invisibility duration.
Nyx Assassin
* Impale and Spiked Carapace can be used to cancel Dismember easily, and can even do so when Pudge uses it on Nyx Assassin, if timed correctly.
Keeper of the Light
* Heroes with silences: Puck, Doom, Riki.
Nyx Assassin
* 
Illusory Orb is easy to reflect with Spiked Carapace, either stunning Puck and setting up an easy Impale or forcing a premature 
Phase Shift.
* Puck is an intelligence hero that tends to build intelligence items, making it vulnerable to Mana Burn.
* An ill-timed Phase Shift can easily set Puck up to be stunned by Impale.
* Puck's low base armor and below average agility gain mean it is always susceptible to Vendetta.
Additional:
* Nyx Assassin can take advantage of every one of Puck's weaknesses. His entire skill set is very effective in countering Puck.
* Because Illusory Orb is such a slow moving projectile, Nyx Assassin can simply walk into the orb and activate Spiked Carapace, stunning Puck and setting up an easy Impale. This can be circumvented by using Phase Shift while the orb is traveling, however, that means that Puck cannot use Phase Shift to dodge any other skill nor use it to safely blink away from a fight.
* Puck is an intelligence hero that likes to build intelligence items such as 
Eul's Scepter of Divinity, 
Scythe of Vyse, and Dagon. This makes Mind Flare that much more deadly against Puck.
* An ill-timed Phase Shift can turn into an easy setup for Impale.
Keeper of the Light
* Heroes who are strong against mobile heroes: 
Disruptor, 
Bloodseeker, 
Kunkka, Keeper of the Light.
Nyx Assassin
* Nyx Assassin's high burst damage can be the bane of Dark Willow, as her low health makes it difficult to survive long enough to escape through Shadow Realm.
* Spiked Carapace can be triggered by walking deliberately into Bramble Maze, leaving Dark Willow stunned and defenseless.
Nyx Assassin
* Nyx Assassin can simply activate Spiked Carapace while under many Invoker's abilities to stun him.
* Nyx Assassin takes advantage of Invoker's massive intelligence gain to do tons of damage using Mind Flare, as the spell does more damage based on the target's intelligence.
* Vendetta burns a large amount of Invoker's essential mana pool.
Nyx Assassin
* Nyx Assassin's Spiked Carapace will stun Leshrac when hit by any of his AOE abilities.
* Mind Flare deals high damage due to Leshrac's high intelligence gain.
* Vendetta burns a large amount of Leshrac's essential mana pool.
Nyx Assassin
* The huge physical damage taken from Vendetta will force Necrophos to use Ghost Shroud, which is good for a followup with Dagon and 
Ethereal Blade, both of which are common items on Nyx Assassin.
* Using Ghost Shroud also sets Necrophos up for a Mind Flare or Impale.
Nyx Assassin
* 
Heat-Seeking Missile allow easy Spiked Carapace stuns.
* As a fragile hero that relies on mana and intelligence items, Tinker is vulnerable to Mana Burn.
* Nyx Assassin's stuns can interrupt 
Rearm and leave Tinker helpless.
Additional:
* Nyx Assassin's whole skillset is good against Tinker:
* Impale prevents Tinker from blinding Nyx Assassin or fighting back, while giving Nyx' allies time to catch up to Tinker's position.
* Mind Flare generally deals more damage to intelligence based heroes like Tinker.
* Spiked Carapace can stun Tinker at a moment of Nyx Assassin's choosing if March of the Machines has been cast. It is also quite easy to time Spiked Carapace against Heat Seeking Missiles.
* Vendetta allows Nyx to approach Tinker in the trees or wait for him in common hiding spots and deal heavy damage to his low armor.
Nyx Assassin
* Impale and Spiked Carapace interrupts Upheaval with ease.
* Warlock's low health pool, mobility, and high intelligence gain makes him a prime target for Nyx Assassin's burst damage.
Nyx Assassin
* Vendetta disables Vengeance Aura and allows him to attack Vengeful Spirit with Impale and Mind Flare.
* Spiked Carapace is easy to use against a Wave of Terror or Magic Missile.
Nyx Assassin
* Spiked Carapace reacts on any of the damage over time from Phoenix's abilities and can interrupt 
Sun Ray and 
Icarus Dive.
Nyx Assassin
* Outworld Destroyer's high intelligence gain and fragility makes him an easy target for a massive Mana Burn, as well as killing him outwards with Nyx Assassin's high burst damage.
* 
Astral Imprisonment can be easily exploited by Nyx Assassin with his abilities. As long as Astral Imprisonment was not cast on Nyx Assassin, it will make an opportunity for an easy stun, either by Spiked Carapace (if Outworld Destroyer hid his allies or your allies) or Impale (if he hid himself). If Astral Imprisonment was cast on Nyx Assassin, using Spiked Carapace while banished will proc the stun after the disable, since Spike Carapace has a 0 second cast time and Astral Imprisonment deals damage right after the disable ends.
* An ill-timed 
Sanity's Eclipse and/or well timed Spiked Carapace can deal a lot of damage to Outworld Destroyer and stun him, unless Outworld Destroyer used Black King Bar beforehand.
Additional:
* Outworld Destroyer's high intelligence makes him a good target for Mind Flare.
* If timed correctly, Spiked Carapace will return the full damage from Sanity's Eclipse back to Outworld Destroyer. Even a reflected Arcane Orb can deal significant damage and make him vulnerable to a follow-up from Nyx Assassin.
* Spiked Carapace is also the perfect tool against Astral Imprisonment: if used on Nyx, he can reflect the damage back as he comes out of the prison by casting the ability while imprisoned.
Nyx Assassin
* Nyx Assassin has a lot of burst damage from his Impale, Mind Flare, Dagon, and the bonus damage from Vendetta. All of this damage is enough to kill Drow Ranger.
* Nyx Assassin is usually invisible most of the time thanks to his ability Vendetta, which allows him to gank Drow Ranger easily.
* However, 
Gust is extremely dangerous for Nyx Assassin, as it's silence can render Nyx Assassin unable to lock down Drow Ranger. And if Gust hits Nyx Assassin while he is invisible with Vendetta, Drow Ranger will be able to detect him and foil his ganking attempts on her because Gust reveals invisible units.
Nyx Assassin
* Ravage's travel time allows Nyx Assassin to easily stun Tidehunter with Spiked Carapace.
* Vendetta can instantly deplete Tidehunter's low mana pool, especially in the early game, potentially preventing Tidehunter from casting Ravage.
Keeper of the Light
* Melee carries during the laning phase: Sven, Slark
Keeper of the Light
* Certain heroes can mess up with Pangolier's positioning and timing (especially if he intends to use Rolling Thunder during combat): 
Vengeful Spirit, Keeper of the Light, Huskar, Dark Seer
Nyx Assassin
* Large area-of-effect with delay or require channeling: Enigma, Crystal Maiden, 
Invoker, Shadow Fiend, Pugna, Keeper of the Light, Dawnbreaker.
Keeper of the Light
* Any hero who can counter-initiate in anticipation without getting caught in Reverse Polarity: Sven, Omniknight, Enigma, Luna, Naga Siren, 
Mars, Jakiro, Venomancer, 
Elder Titan, 
Faceless Void, 
Rubick, Keeper of the Light, Pugna, Invoker, Spectre, 
Alchemist, Treant Protector, Lina, Oracle, 
Zeus, 
Shadow Shaman, 
Phoenix, 
Razor, Huskar, 
Batrider, Kunkka, 
Tidehunter, 
Wraith King, Sand King, Medusa, Dawnbreaker.
Nyx Assassin
* Slow-moving projectiles: 
Skywrath Mage, Tinker, 
Necrophos
Additional:
* Skywrath Mage's low health makes him rather easy prey for Nyx Assassin and his lack of armor generally means he'll take the full brunt of a Vendetta strike.
* Mind Flare turns Skywrath Mage's high intelligence growth against him and deals heavy damage.
* Spiked Carapace gives Nyx some degree of protection against Skywrath's spells.
Keeper of the Light
* Heroes with teleports to escape Solar Blind and Will-O-Wisp: Phantom Assassin, Puck, 
Queen of Pain, 
Storm Spirit
Nyx Assassin
* Heroes with heavy early and mid-game magical damage are also problematic for Phantom Assassin due to being able to easily kill her before she can gain an item advantage over them: Lina, Necrophos, Nyx Assassin, 
Gyrocopter, Jakiro, 
Death Prophet.
Keeper of the Light
* Heroes which rely exclusively on right clicks will struggle somewhat against Blinding Light: Phantom Assassin, Wraith King, Medusa
Nyx Assassin
* Heroes that can pick you off: Clinkz, Nyx Assassin, Puck, Riki.
Nyx Assassin
* Heroes with silence and mana drain abilites, as Ancient Apparition relies entirely on his abilities: Invoker, Silencer, Nyx Assassin, Skywrath Mage, Shadow Shaman, Lion and etc.
Keeper of the Light
* Heroes that punish mobile heroes: Bloodseeker, Keeper of the Light, Kunkka, Disruptor.
Nyx Assassin
* Heroes with either magical, physical or pure damage burst: 
Bane, Ember Spirit, 
Leshrac, Lina, Luna, Nyx Assassin, Phantom Assassin, Skywrath Mage, Tinker, 
Ursa, 
Void Spirit.
Nyx Assassin
* Heroes who can drain mana can make Omniknight useless after he uses one or two abilities: Lion, Anti-Mage, Nyx Assassin.
Keeper of the Light
* Heroes which rely exclusively on right clicks will struggle somewhat against Blinding Light: Phantom Assassin, Wraith King, Medusa
Nyx Assassin
* Nyx Assassin, Bounty Hunter and Slark can all sneak up and kill Shadow Shaman, Nyx being particularly deadly. Shadow Shaman must watch out for Slark carefully, as he can break either (but not both unless he makes a mistake) of Shadow Shaman's disables, with 
Dark Pact and leap out of a serpent ward ring. These heroes, however, rely heavily on escape and are themselves not very durable and none of them can survive a full lockdown with Mass Serpent Ward. Having Sentry Wards can turn Shadow Shaman from prey to predator.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Jakiro, Viper, Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.
Nyx Assassin
* With Vendetta, Nyx Assassin can move closely to Ember Spirit when he's farming with his Flame Guard and use Spiked Carapace with Impale to provide a reliable and long disable.
Additional:
* Spiked Carapace can be easily triggered by 
Flame Guard or Battle Fury, setting up a deadly Impale.
Keeper of the Light
* Heroes with teleports to escape Solar Blind and Will-O-Wisp: Phantom Assassin, Puck, Queen of Pain, Storm Spirit
Nyx Assassin
* A good Nyx can reflect Queen of Pain's Sonic Wave with his Spiked Carapace, or even initiate a gank on her in Vendetta while she farms a creep wave with Scream of Pain.
* Her strength to intelligence ratio is bad enough that he should be able to kill her without even requiring a Dagon, provided he can get his full combo off.
Keeper of the Light
* Heroes with channeling abilities: Enigma, Witch Doctor, Crystal Maiden.
Nyx Assassin
* Crystal Maiden has a very bad movement speed, so Impale is easy to land against her. Furthermore, even while trapped by Frostbite, Nyx Assassin can still cast Impale.
* Crystal Maiden has very low armor, so Vendetta is very effective.
* Nyx Assassin has two ways to stop Freezing Field, provided she doesn't get a Black King Bar. He can either pop Spiked Carapace and simply walk into the field, or he can use Impale to interrupt the field, since Crystal Maiden has to channel it.
Additional:
* Spiked Carapace easily interrupts 
Freezing Field.
* 
Frostbite's damage over time sets up an easy Spiked Carapace stun.
* Crystal Maiden is extremely fragile and dies quickly to Nyx Assassin's burst damage.
Keeper of the Light
* Heroes with teleports to escape Solar Blind and Will-O-Wisp: Phantom Assassin, Puck, Queen of Pain, Storm Spirit
Nyx Assassin
* Mana Burn removes much-needed mana for 
Ball Lightning.
* Spiked Carapace triggers on 
Static Remnant for an easy stun.
Additional:
* Vendetta is capable of removing most of Storm Spirit's large mana pool, along with dealing heavy damage and quickly depleting his chances of escaping a gank or fight.
Nyx Assassin
* Heroes who build Black King Bar as either core or situational item will be able to fight back against Nyx Assassin and freely attack him as Spiked Carapace cannot pierce spell immunity at all: Axe, Broodmother, Dawnbreaker, Enigma, Huskar, Jakiro, Legion Commander, Lina, Luna, Lycan, Slardar, Slark, Troll Warlord, Witch Doctor.
Nyx Assassin
* Mind Flare does tons of damage against Lina because of her high intelligence.
* Vendetta can deal heavy damage to Lina while also burning her mana, preventing Lina from casting her abilities.
* Spiked Carapace can easily be used to counter Lina's abilities because of their long cast animation, and could probably kill Lina outright if Laguna Blade is reflected. However, Lina can counter this with Eul's Scepter of Divinity, a common item on Lina.
Nyx Assassin
* Heroes who build Black King Bar as either core or situational item will be able to fight back against Nyx Assassin and freely attack him as Spiked Carapace cannot pierce spell immunity at all: Axe, Broodmother, Dawnbreaker, Enigma, Huskar, Jakiro, Legion Commander, Lina, Luna, Lycan, Slardar, Slark, Troll Warlord, Witch Doctor.
Keeper of the Light
* Heroes with channeling abilities: Enigma, Witch Doctor, Crystal Maiden.
Nyx Assassin
* Enigma is fragile, and lacks escapes, being dependent on Blink Dagger for mobility. Ganking Heroes or Heroes with burst damage will likely kill him before he can do anything. Such Heroes include: Lina, Lion, Luna, Puck, Slark, Nyx Assassin, etc.
Additional:
* Enigma's uncontrollable damage from 
Malefice and 
Midnight Pulse make him easy to stun with Spiked Carapace.
* 
Black Hole can be easily interrupted by Impale or Spiked Carapace.
Keeper of the Light
* Illuminate can wipe the pushing Eidolons in a lane with ease, diminishing Enigma's laning presence by a lot.
* Solar Bind will severely slow down Enigma and make him more vulnerable to magical damage more he moves for it's duration.
* However, Keeper of the Light does not have any way to cancel Black Hole outside from Will-O-Wisp provided by Aghanim's Scepter.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Jakiro, Viper, Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.
Nyx Assassin
* Spiked Carapace can stop Dawnbreaker's Solar Guardian which will eliminate her global presence and limits her movement around the map.
Additional:
* Spiked Carapace interrupts 
Starbreaker before Dawnbreaker has her Aghanim's Shard, as well as 
Solar Guardian during the initial channel, making her ineffective at joining and dealing damage in teamfights.
* The slow projectile and damage over time effect of 
Celestial Hammer makes it easy to stun Dawnbreaker if she attemps to engage or chase.
Nyx Assassin
* With Aghanim's Scepter, Broodmother will gain access to 
Spinner's Snare, which will allow her to create invisible lines on her webs from 
Spin Web that will root, deal damage over time, and reveal enemy heroes if they unwittingly step on them. This allows Broodmother to keep her allies alerted on heroes who rely on invisibility-themed and movement-themed abilities and items to surprise enemy heroes and disrupt ganking attempts of enemy heroes: Phantom Assassin, Nyx Assassin, 
Mirana, Bounty Hunter, Templar Assassin, Riki, Spirit Breaker, Anti-Mage, 
Tusk, Ursa, Nature's Prophet, Enigma, Void Spirit, Magnus etc.
Keeper of the Light
* Illuminate wipes out Broodmother's spiders and prevents her from pushing the lane. It also gives vision to reveal where broodmother is hiding in the trees.
Nyx Assassin
* Heroes who rely on invisibility, such as Bounty Hunter, Clinkz, Mirana, Nyx Assassin and Riki, as they will be revealed if caught by Chronosphere.
Keeper of the Light
* Any hero that can nullify effects of Chronosphere: (Keeper of the Light with Aghanim's Scepter during daytime, 
Winter Wyvern), banishing him or Faceless Void (
Outworld Destroyer, 
Shadow Demon, 
Earth Spirit with Aghanim's Scepter) or protecting him in other ways (
Dazzle, Oracle, 
Abaddon) can greatly limit Chronosphere's potential.
Nyx Assassin
* Nyx Assassin's skillset is mostly single-targeted, therefore he will have difficulties against heroes with illusions and summons: Naga Siren, Broodmother, Lycan, Visage, Phantom Lancer. And to make things worse, Nyx Asassin is not a common Battle Fury, Maelstrom, Mjollnir, Gleipnir or Radiance wielder to counter this problem.
Keeper of the Light
* Keeper of the Light can stall pushes with Illuminate. This makes him strong against pushing heroes: Terrorblade Naga siren Nature's Prophet and Anti-Mage
Keeper of the Light
* Any hero who lanes very poorly will struggle with Primal Beast's potential snowball in the very early levels, like Keeper of the Light, Luna, Templar Assassin...
Nyx Assassin
* Like above, supports with reliable stuns can be a massive problem and force Black King Bar in fights unideally, such as Shadow Shaman, Lion, Nyx Assassin.
Keeper of the Light
* Pugna easily copes on the line with the Keeper of the Light push with his 
Nether Blast, and in addition to 
Nether Ward, the Keeper of the Light is not able to throw Illuminate on creeps for a long time, so Pugna earns more gold and a level on the line
Additional:
* Pugna easily copes on the line with the Keeper of the Light push with his Nether Blast, and in addition to Nether Ward, the Keeper of the Light is not able to throw Illuminate on creeps for a long time, so Pugna earns more gold and a level on the line
Nyx Assassin
* Nether Blast's animation makes it easy to time Spiked Carapace for a stun.
* Pugna has the largest intelligence gain in the game, making him a prime target for Mana Burn.
* Pugna needs to channel 
Life Drain, making him easy to hit with Impale.
Additional:
* Due to Pugna's incredible intelligence growth and terrible strength growth, Nyx should always be able to take you out with his combo, with or without an added Dagon. Mind Flare will deal a large amount of damage in particular, especially in the late game.
* Spiked Carapace is also a great tool versus Pugna. A good player will wait for you in Vendetta until you farm a creep wave with Nether Blast and reflect it back at you as their initiation and setup for Impale.
Nyx Assassin
* 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.
Nyx Assassin
* Heroes with magical or pure damage output will not have any problems against Atrophy Aura at all: Luna, Lina, Jakiro, Pugna, Bane, 
Snapfire, 
Muerta, Nyx Assassin, Enigma, Tinker, Witch Doctor, Zeus, Crystal Maiden.
Nyx Assassin
* 
Corrosive Skin minimizes the damage from Impale and Mind Flare, and anything else Nyx Assassin tries to throw at Viper.
* Nyx Assassin cannot survive several poison damage-over-time output from 
Poison Attack, 
Nethertoxin, Corrosive Skin and 
Viper Strike, not even while he has Spiked Carapace active. And to make things worse, Nyx Assassin is not a common 
Silver Edge wielder to counter this problem at all.
Additional:
* Corrosive Skin minimizes the damage from Impale and Mind Flare, and anything else Nyx Assassin tries to throw at Viper.
* Nyx Assassin cannot survive several poison damage-over-time output from Poison Attack, Nethertoxin, Corrosive Skin and Viper Strike, not even while he has Spiked Carapace active. And to make things worse, Nyx Assassin is not a common Silver Edge wielder to counter this problem at all.
Keeper of the Light
* The Keeper of the Light easily farms on the line against the Viper, due to the fact that it has a long-range Illuminate, and the Viper, in turn, cannot use its advantage of dominance on the center line, due to the fact that it does not reach the Keeper of the Light
Additional:
* The Keeper of the Light easily farms on the line against the Viper, due to the fact that it has a long-range Illuminate, and the Viper, in turn, cannot use its advantage of dominance on the center line, due to the fact that it does not reach the Keeper of the Light
Keeper of the Light
* Being a cast-oriented hero, Ezalor will suffer from all of Silencer's abilities.
* 
Global Silence is a guaranteed lengthy silence which will render Ezalor useless in a teamfight.
* 
Arcane Curse and 
Last Word are good against any caster, since they are extremely potent.
* However, it should be worth mentioning that a smart Ezalor will buy Eul's Scepter of Divinity to dispel Silencer's abilities. Combined with the level 20 talent (Chakra Magic applies a basic dispel), Ezalor can purge Silencer's abilities off allies and himself alike.
Nyx Assassin
* Last Word is extremely easy to reflect with Spiked Carapace for large amounts damage, due to triggering when Nyx Assassin casts a spell, but can still silence Nyx Assassin. It also has the added bonus of dealing more damage the more Intelligence Silencer has.
* 
Glaives of Wisdom quickly builds Silencer's Intelligence, making him a particularly prime target for Mana Burn.
* Silencer rarely builds survivability items, nor is he able to steal much Intelligence while surrounded by his team, and so is an excellent target for Vendetta.
* Silencer has no reliable way of dealing with a burrowed Nyx, and also lacks the ability to prevent Nyx from escaping with Vendetta,
Additional:
* Silencer is rather squishy and has poor mobility without items, making him an easy target for Nyx.
* Silencer's intelligence steal ability is a complete disadvantage against Nyx Assassin as Mind Flare will deal increasing damage for each point of intelligence Silencer has stolen, turning Silencer's intelligence steal against him.
Nyx Assassin
*
Rage allows Lifestealer to freely attack Nyx Assassin and hunt him down if Vendetta is on cooldown. Nyx Assassin cannot counter 
Rage with Spiked Carapace because 
Rage gives Lifestealer spell immunity. And besides Vendetta, Nyx Assassin has no other way of dealing damage to Lifestealer while he is spell immune.
Open Wounds from 
Aghanim's Shard allows Lifestealer to severely slow down Nyx Assassin while also allowing his team to recover themselves while attacking Nyx Assassin. 
Open Wounds can also fester and spread if Nyx Assassin takes enough damage that will trigger the spread while he is affected with 
Open Wounds.
Infest combined with an ancient creep makes Nyx Assassin an easy target to surprise with 
Dust of Appearance or a 
Gem of True Sight. 
Aghanim's Scepter upgraded 
Infest can also allow Lifestealer to infest, disarm and freely attack Nyx Assassin from within. and Nyx Assassin cannot counter this with Spiked Carapace because Lifestealer is invulnerable while attacking the infested enemy hero from within.
Blade Fury, 
Rage allows Lifestealer to freely attack Nyx Assassin and hunt him down if 
Vendetta is on cooldown. Nyx Assassin cannot counter 
Rage with 
Spiked Carapace because 
Rage gives Lifestealer spell immunity. And besides 
Vendetta, Nyx Assassin has no other way of dealing damage to Lifestealer while he is spell immune.
Open Wounds from 
Aghanim's Shard allows Lifestealer to severely slow down Nyx Assassin while also allowing his team to recover themselves while attacking Nyx Assassin. 
Open Wounds can also fester and spread if Nyx Assassin takes enough damage that will trigger the spread while he is affected with 
Open Wounds.
Infest combined with an ancient creep makes Nyx Assassin an easy target to surprise with 
Dust of Appearance or a 
Gem of True Sight. And similarly to Juggernaut's 
Omnislash and 
Swiftslash from 
Aghanim's Scepter, 
Aghanim's Scepter upgraded 
Infest can also allow Lifestealer to infest, disarm and freely attack Nyx Assassin from within. And Nyx Assassin cannot counter this with 
Spiked Carapace because Lifestealer is invulnerable while attacking the infested enemy hero from within.
*
*
* Overall, any attempt for Nyx Assassin to gank and kill Lifestealer will hurt Nyx Assassin more than Lifestealer.
Additional:
* Like with Juggernaut's
*
*
* Like with Juggernaut, any attempt for Nyx Assassin to gank and kill Lifestealer will hurt Nyx Assassin more than Lifestealer.
Keeper of the Light
*
Rage allows him to be immune to all of Ezalor's abilities. Also, the increased movement speed combined with the slow from 
Ghoul Frenzy and the squishy nature of Ezalor allows Lifestealer to take him down very quickly.