Axe
* 
Poison Attack and 
Viper Strike slows Axe significantly, and puts his 
Blink Dagger on cooldown, preventing him from initiating.
* 
Nethertoxin can break Counter Helix.
Additional:
* Nethertoxin prevents 
Counter Helix from triggering, which significantly lowers Axe's damage output in the early to mid game.
* Viper's various slows and damage over time prevents Axe from initiating as well as putting his Blink Dagger on cooldown.
Nyx Assassin
* 
Corrosive Skin minimizes the damage from 
Impale and 
Mind Flare.
* Nyx Assassin cannot survive several poison damage-over-time, even 
Spiked Carapace is activated.
Axe
* 
Infernal Blade's damage is calculated by a percentage of maximum health, meaning that it will hurt Axe more than most normal attacks, negating some of his durability.
* Doom can pick up several different abilities from neutral creeps using 
Devour, some of which can be annoying to Axe.
* Mud Golem, Dark Troll Summoner, Harpy Stormcrafter, Satyr Mindstealer or Satyr Tormenter are good examples.
* Doom's naturally low attack speed makes Counter Helix less likely to proc, and his high base health allows him to take a few Helixes with no danger.
* 
Doom makes Axe less disruptive, preventing him from using his skills or items. At level 25, there is a branch of the talent tree that makes Doom apply Break, allowing Doom to disable Counter Helix, making Axe effectively useless for a lengthy duration.
Additional:
* Infernal Blade deals scaling damage and is useful against high HP targets such as Axe.
* Doom has low attack speed because of his high Base-Attack-Time, poor agility gain and limited attack-speed granting items which are commonly built. This means Doom will trigger Counter Helix less often and thus is an unideal target for initiation.
* Doom has naturally high HP so it takes longer for Doom to be brought down to the killing threshold of 
Culling Blade.
* Axe is highly reliant on his abilities and items to be effective during a fight. Without the usage of 
Berserker's Call and Blink Dagger due to Doom, Axe offers very little in the way of damage, effectively removing him from a fight.
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.
Axe
* 
Ice Path is a great stun for Berserker's Call and with a 
Eul's Scepter of Divinity can really catch Axe off guard.
* 
Dual Breath and 
Liquid Fire can be a devastating combination for Axe (especially if he takes Battle Hunger at level 1) before he has any natural regeneration sustain from items.
Additional:
* Ice Path neutralizes initiation attempts with Berserker's Call, and its long area of effect discourages follow-ups from Axe's teammates until Axe buys 
Black King Bar.
* Ice Path serves as a large obstacle to stop Axe from chasing down fleeing stragglers to kill with Culling Blade until Axe buys Black King Bar.
* Jakiro's many damage-per-second skills prevent Axe from initiating with his Blink Dagger. Forcing Axe to buy Black King Bar prematurely to protect himself against Jakiro's abilities and counter-initiaions.
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.
Axe
* Venomancer's slows and magical damage-over-time work well against Axe's complete lack of mobility.
* 
Plague Ward is especially useful for slowing down Axe, and revealing him before he initiates, as well as putting his Blink Dagger on cooldown.
Additional:
* Venomancer's slows and magical damage-over-time work well against Axe's complete lack of mobility.
* Plague Wards is especially useful for slowing down Axe, and revealing him before he initiates, as well as putting his Blink Dagger on cooldown.
* For the same reasons, Venomancer is a good ally for Axe when the situation is reversed.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: 
Venomancer, Huskar, 
Ember Spirit, 
Dark Seer, 
Sand King, 
Doom, Dawnbreaker. However, this also means they are easily stunned.
Axe
* 
Crippling Fear makes it so Axe might use Blink Dagger right into an AoE silence in the middle of everyone.
* 
Void cripples Axe's already bad movement speed and attack speed.
* 
Hunter in the Night makes it impossible for Axe to catch up to fleeing or escape from Night Stalker during the night.
* Lastly, 
Dark Ascension gives full vision over Axe before he initiates, making the opponents all recognize his location immediately and allowing Night Stalker to prevent it or vocally tell his team if needed.
* Night Stalker has very high strength gain, even in the lane, so a successful Culling Blade is very unlikely.
* Axe's 
Blade Mail will likely do nothing to Night Stalker because of his high health and certain requirements for him to do the most damage to be true.
Nyx Assassin
* Heroes that have a weak laning stage: 
Spectre, 
Nyx Assassin, 
Clockwerk, 
Spirit Breaker, 
Omniknight, 
Pudge.
Axe
* Long lockdown is a great way to deal with Axe to prevent Berserker's Call from being used, heroes such as Legion Commander, 
Beastmaster and 
Primal Beast are good examples of this.
Nyx Assassin
* Duel's long duration prevents Nyx Assassin escaping from 
Vendetta. With Aghanim's Scepter, she can also bypass Spiked Carapace.
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.
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
* 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
* 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 attempts with Vendetta, making him an easy kill for gold as well.
Nyx Assassin
* 
Cyclone from Storm in 
Primal Split can waste Nyx's Spiked Carapace, since its duration is shorter than the Cyclone's.
Axe
* 
Enrage reduces the damage from Blade Mail and Counter Helix to a minimum, forcing Axe to play around Ursa's ultimate ability.
* 
Overpower and 
Fury Swipes stacks damage overwhelming for Axe, despite his high health.
Axe
* 
Disruption will save Shadow Demon's teammates from being killed by Counter Helix or Culling Blade.
* 
Demonic Purge slows Axe to a crawl, making him nearly useless after initiating. If Shadow Demon has Aghanim's Scepter, it will also break Counter Helix.
* 
Demonic Cleanse clears Battle Hunger and Aghanim's Shard Counter Helix Damage Reduction, both allowing targets to escape and reducing your own survivability.
Additional:
* While it is unwise to encounter Axe alone, Disruption can be used to save your allies from Axe's initiate Berserker's Call, or, if timed correctly, from his Culling Blade.
* Illusions spawned from Axe has the Counter Helix passive, which with deal some nasty damage if an enemy focuses them
* Your upgraded Demonic Purge breaks Axe's primary damage output: Counter Helix, This can be used on him during Berserker's Call to seriously hinder him.
* Demonic Cleanse will clear 
Battle Hunger, which is Axe's method of catching heroes, and Shard upgraded Counter Helix's Damage Reduction, which is one of Axe's primary survivability abilities.
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.
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.
Axe
* Heroes who can stop Axe from getting close will severely inhibit his presence in fights: 
Bristleback, 
Crystal Maiden, 
Batrider, 
Arc Warden, 
Winter Wyvern, Clockwerk
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.
Axe
* Heroes that relies on armor or other type of physical damage negation are easy for Gyrocopter to take down during the early game with his magical damage: Axe, 
Dragon Knight, 
Sven.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.
Axe
* Because Exorcism's damage is not reduce by damage block abilities or items, Death Prophet can be very good against heroes who rely on armor to survive: Axe, 
Terrorblade, 
Morphling, Dragon Knight
Axe
* Heroes who can stop Axe from getting close will severely inhibit his presence in fights: Bristleback, Crystal Maiden, Batrider, Arc Warden, Winter Wyvern, Clockwerk
Nyx Assassin
* In general, attacks of the melee 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, and will 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.
Axe
* Ranged heroes that can easily harass Axe: Drow Ranger, 
Sniper, 
Lion.
Axe
* Long lockdown is a great way to deal with Axe to prevent Berserker's Call from being used, heroes such as Legion Commander, Beastmaster and Primal Beast are good examples of this.
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.
Axe
* Special mention to 
Timbersaw as he has a way to deal with Axe in the laning stage, but still needs to be careful about Berserker's Call stun, the pure damage from Counter Helix and Culling Blade finishing him off before he can escape or heal from his passive.
Additional:
* 
Whirling Death reduces Axe's strength by 15%, which makes him less durable, especially from early game. It's also stackable.
* Blade Mail are not effective against attribute changes, and 
Timber Chain can wait out Blade Mail's duration to wear off.
* 
Reactive Armor makes it harder for Axe to finish off Timbersaw with Culling Blade.
* 
Chakram disarms Timbersaw, which makes Axe's Counter Helix useless against him.
* All Timbersaw skills deal pure damage, which bypass Axe's high armor or bonus armor from Berserker's Call.
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.
Axe
* Melee heroes who rely on summons, illusions, or clones will trigger Counter Helix more often, thus taking more damage: 
Meepo, Lycan, Phantom Lancer
Additional:
* Berserker's Call can keep Lycan in place during his Shapeshift even through Black King Bar.
* Counter Helix is very effective against Lycan because of his summons.
* Culling Blade will prevent Lycan from running away with Shapeshift when he drops low.
Axe
* Omniknight's healing prevents allies from dropping low enough for Culling Blade
* 
Heavenly Grace dispels Battle Hunger.
* Axe also tends to get close to allied heroes in order to damage them with his Counter Helix, which can easily be punished by Purification.
Nyx Assassin
* Heroes who can drain mana can make Omniknight useless after he uses one or two abilities: Lion, 
Anti-Mage, Nyx Assassin.
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.
Axe
* Heroes who rely on fast attack speed will also trigger Counter Helix frequently: 
Faceless Void, Troll Warlord, Anti-Mage, 
Juggernaut, Arc Warden, Morphling
Additional:
* Berserker's Call pierces spell immunity, making a Blade Fury teleport escape impossible. It's very useful against Omnislash as well.
* Juggernaut's low base health and high attack speed causes him to take a lot of damage from Counter Helix.
* Axe is a common Blade Mail and Blink Dagger carrier making him a very big potential threat before Juggernaut get his items.
Axe
* Terrorblade's low base health and lack of mobility make him an easy target for Axe to initiate on, and kill.
* Counter Helix will trigger from, and destroy many of Terrorblade illusions.
Additional:
* Berserker's Call and Counter Helix together can be devastating to Terrorblade, especially if Terrorblade has a lot of illusions. Their high attack speed will trigger Counter Helix a lot, and the pure damage will quickly slice through Terrorblade's low health and kill his illusions. More importantly, the Berserker's Call can pierce through spell immunity from Black King Bar, Terrorblade's only survival item besides Manta Style which cannot be used to dispel Berserker's Call. With enough burst damage by Axe's teammates, Terrorblade can be finished off even before taunt duration runs out and he gets a chance to save himself with 
Sunder.
* Culling Blade can finish off Terrorblade before he has the chance to Sunder due to his low health in the early to mid game. And every time Terrorblade or any of his allies are successfully killed by Culling Blade, Axe permanently gains armor from it, which in combination with armor items that Axe often purchases like Blade Mail, 
Crimson Guard, 
Assault Cuirass and 
Shiva's Guard can make Terrorblade's attacks only tickle Axe, even during Metamorphosis.
* Terrorblade's low base health and lack of mobility make him an easy target for Axe to initiate on, and kill.
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.
Axe
* Berserker's Call forces Dark Willow to attack, cancelling Shadow Realm.
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.
Axe
* 
Windrun does not provide protection against Counter Helix and Berserker's Call. Her fast attack speed with Focus Fire will also quickly trigger Counter Helix multiple times.
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.
Axe
* Most of the Axe's abilities can affect Muerta during Pierce the Veil, except for Battle Hunger which deals physical damage.
* While Muerta can do much damage to highly armored units, Axe has a larger health pool compared to Muerta and can activate Berserker's Call and Blade Mail to turn Muerta's attack damage against her.
* Counter Helix takes advantage of Muerta's high attack speed from both stats and items.
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 abuses Muerta's high intelligence to make 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.
Axe
* Berserker's Call is one of the best ways to lock down Weaver before he has a chance to use 
Time Lapse. It can also catch Weaver in 
Shukuchi.
* Weaver's high attack speed, along with high attack damage from 
Geminate Attack, triggers Counter Helix continuously and the output damage would be returned by Blade Mail.
Additional:
* Berserker's Call is one of the best ways to lock down Weaver before he has a chance to use Time Lapse. It can also catch Weaver in Shukuchi.
* Due to his fast attack speed from Geminate Attack and items that give attack speed, Counter Helix will activate a lot, and the damage would be returned by Blade Mail, which hurts Weaver far more than it hurts Axe.
* Culling Blade can finish off Weaver's low health pool before he escapes with Shukuchi and Time Lapse.
* Battle Hunger is a good tool to pop Weaver's 
Linken's Sphere due to its low cooldown.
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.
Axe
* 
Phantom Strike's extra attack speed will cause Phantom Assassin to trigger Counter Helix more often, which can be fatal for Phantom Assassin. Jumping on Axe with Phantom Strike is not a good idea for Phantom Assassin at all as it makes her a seriously easy target for a counter-initiation with Berserker's Call and Blade Mail.
* Most of Axe's abilities pierce Black King Bar, allowing him to lock down Phantom Assassin at any time.
* Berserker's Call greatly reduces Phantom Assassin's ability to crit hard against Axe and may cause her to kill herself when used with Blade Mail. Berserker's Call can also affect Phantom Assassin even if she has Black King Bar active as Berserker's Call can fully pierce spell immunity, making Berserker's Call one of the best abilities in the game against heroes like Phantom Assassin who wants to kill opponents quickly without being interrupted.
* Culling Blade can often kill Phantom Assassin before she can do anything due to her low health and strength gain. And every time Culling Blade successfully kills Phantom Assassin or any of her teammates, Axe gains permanent armor from it, which in combination with armor items that Axe often purchases like Blade Mail, Crimson Guard, Assault Cuirass and Shiva's Guard can make Phantom Assassin's attacks only tickle Axe.
* 
Aghanim's Shard upgraded Counter Helix can weaken Phantom Assassin's damage output, and if her attack damage is weak, 
Coup De Grace will also suffer from attack damage reduction as well.
Additional:
* Phantom Strike's extra attack speed will cause Phantom Assassin to trigger Counter Helix more often, which can be fatal for Phantom Assassin in the early game. Jumping on Axe with Phantom Strike is not a good idea for Phantom Assassin at all as it makes her a seriously easy target for a counter-initiation with Berserker's Call and Blade Mail.
* Most of Axe's abilities pierce Black King Bar, allowing him to lock down Phantom Assassin at any time.
* Berserker's Call greatly reduces Phantom Assassin's ability to crit hard against Axe, and may cause her to kill herself when used with Blade Mail. Berserker's Call can also affect Phantom Assassin even if she has Black King Bar active as Berserker's Call can fully pierce spell immunity, making Berserker's Call one of the best abilities in the game against heroes like Phantom Assassin who wants to kill opponents quickly without being interrupted.
* Culling Blade can often kill Phantom Assassin before she can do anything due to her low health and strength gain. And every time Culling Blade successfully kills Phantom Assassin or any of her teammates, Axe gains permanent armor from it, which in combination with armour items that Axe often purchases like Blade Mail, Crimson Guard, Assault Cuirass and Shiva's Guard can make Phantom Assassin's attacks only tickle Axe.
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.
Axe
* Axe, Bristleback, 
Centaur Warrunner, Spirit Breaker, Pudge, Huskar, Wraith King: These heroes are too tanky for Puck to burst down. Also, all of them have spells which can deal with and shut Puck down reliably.
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.
Axe
* Berserker's Call and Counter Helix allow Axe to kill Shadow Fiend if he stands too close to a creep wave.
* Battle Hunger is can be strong against Shadow Fiend in the early game because Shadow Fiend's low attack damage makes it hard for him to get last hits if he has no mana. However, Shadowraze also makes it very easy for him to get last hits, so use with caution.
* Axe's naturally high strength and health regeneration will be enough to tank a lot of Shadow Fiend's damage in the early game.
Nyx Assassin
* Large area-of-effect with delay or require channeling: Enigma, Crystal Maiden, 
Invoker, 
Shadow Fiend, 
Pugna, 
Keeper of the Light, Dawnbreaker.
Axe
* 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 prevents Queen of Pain from escaping with Blink and also pierces her Black King Bar.
* Due to her fast attack speed from 
Mjollnir, it will quickly trigger Counter Helix.
* Culling Blade finishes off Queen of Pain's low health pool before she gets a chance to escape, preventing her from playing the hit-and-run style often associated with Queen of Pain.
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.
Axe
* Berserker's Call and Counter Helix will still hit targets inside of a defensive 
Sprout.
* Counter Helix clears treants in no time.
* Nature's Prophet's low damage is unlikely to hurt Axe until the very late game.
* Nature's Prophet's low mobility makes him very easy for Axe to chase down or initiate, especially when affected by Battle Hunger.
Nyx Assassin
* Heroes with invisibility: (
Riki, 
Clinkz, Nyx Assassin.
Axe
* Axe can take advantage of Chen jungling and gank him more often with Blink Dagger and Berserker's Call combination.
* Counter Helix can clear waves of Chen's creeps if they are too close to Axe.
* Berserker's Call combined with Blade Mail and Culling Blade can often kill Chen before he can save himself with 
Hand of God.
* However, Hand of God and 
Divine Favor can make it hard for Axe to finish off Chen's allies with Culling Blade when Chen is not target for Axe.
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.
Axe
* Ranged heroes that can easily harass Axe: Drow Ranger, Sniper, Lion.
Axe
* Berserker's Call forces Drow Ranger to attack Axe up close, disabling her Marksmanship bonus.
* Counter Helix occurs more often with Drow Ranger's high attack speed.
* Culling Blade is a dangerous ability against a low health hero like Drow Ranger.
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.
Axe
* Ranged heroes that can easily harass Axe: Drow Ranger, Sniper, Lion.
Axe
* Axe can easily close the distance to Sniper with Blink Dagger.
* With Berserker's Call in combination with Counter Helix and Battle Hunger, Axe can make short work of Sniper, finishing him off easily with Culling Blade due to his low HP & high attack speed in the late game.
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.
Axe
* Pudge, Legion Commander and Axe will make the match a living hell for Shadow Shaman, since they are known for surprise attacks from the fog and quickly killing low HP heroes. They can also interrupt Shadow Shaman's channeling, Legion being especially problematic, as she can use 
Press the Attack on an ally who is hexed as well.
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.
Axe
* Heroes that are hard to gank: Axe, 
Death Prophet, Phantom Lancer
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
* 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.
Axe
* Berserker's Call forces Mars to face in the direction choosen.
* Counter Helix deals pure damage and can go through Bulwark.
Nyx Assassin
* Spiked Carapace stops Snapfire's 
Mortimer Kisses.
Axe
* Berserker's Call prevents Sven from bursting his targets before Axe can interfere. The worst kind of opponent for Sven is one who can stop him from attacking who he wants to, which is exactly what Axe does.
* Culling Blade may finish off Sven before he has the chance to lifesteal or run with Warcry.
* Axe is a very common Blade Mail carrier which will make very short work of a Sven with God's Strength activated.
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.
Axe
* Jumping on Axe with 
Waveform will make Morphling an easy target for a counter-initiation with Berserker's Call.
* Morphling is often played at low health to maximize the bonuses from 
Attribute Shift (Agility Gain), and also because his abilities cost health to use. This makes him especially vulnerable to Culling Blade.
* However, Morphling is a common Linken's Sphere carrier to block Culling Blade, which may force Axe to use Battle Hunger to pop the Spell Block first.
* Attribute Shift (Agility Gain) gives Morphling no protection against the pure damage of Culling Blade. Its attack speed bonus also means that Counter Helix will proc more often.
Axe
* Mana Shield reduces the effectiveness of Counter Helix.
* Stone Gaze makes it very difficult for Axe to initiate on Medusa and her allies.
Axe
* Axe can take advantage of Medusa's awfully low HP to insta-kill her with Culling Blade, making it extremely difficult for her to farm for items to compensate for the lack of strength during early and mid-game while Axe is continuously harassing around.
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.
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.
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.
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.
Nyx Assassin
* Spiked Carapace can be used to reflect Illuminate damage and stun Keeper of the Light.
* Vendetta allows Nyx Assassin to follow Keeper of the Light around if he tries to split-push.
* Keeper of the Light is very squishy and will very quickly die to Vendetta and it's followup abilities.
Axe
* Axe can force Alchemist to attack him with Berserker's Call. High attack speed from 
Chemical Rage will cause Counter Helix to proc multiple times.
* This can get worse if axe has Blade Mail, which then returns all damage to Alchemist himself.
* Axe's abilities can pierce through Black King Bar, which is a common item for Alchemist.
* Berserker's Call grants Axe a huge bonus armor, which greatly counters Alchemist's physical damage for the most part.
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
* 
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
* 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.
Axe
* Culling Blade ignores the protection from 
Shallow Grave and will kill any target whose health is low enough. This makes Axe one of the hardest counters to Dazzle, and he neutralizes one of Dazzle's most important abilities.
Additional:
* Culling Blade kills any target under the health threshold, even through Shallow Grave.
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.
Axe
* Unleash ensures that Axe's Counter Helix procs many times, even if he is stunned by Dispose.
* Aghanim's Shard allows Counter Helix to reduce the attack damage of anyone it strikes. Combined with Unleash causing to proc frequently, Marci will not be dealing significant damage as she attacks Axe over time.
* Axe doesn't worry about the damage from Unleash if he activates Berserker's Call beforehand. If he had activated Blade Mail or Mjollnir (or even both) as Marci attacks him, he will turn Unleash's high attack speed and damage against her.
* Usually, Axe would prefer to jump on his opponent to be more effective. Rebound does Axe a favor, bringing Marci within his most effective range.
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.
Axe
* Axe can disable 
Cloak and Dagger's invisibility with Berserker's Call, which forces Riki to attack him at a very bad angle.
* Axe has a very high HP pool, making it hard for you to kill him before you get big items - that is if you survive engaging him. Counter Helix ignores Riki's armor and goes straight for his tiny HP pool, totally ignoring 
Smoke Screen.
* Axe is a natural buyer of Blade Mail and Riki generally does not buy lifesteal items, causing Riki to kill himself when attacking due to your tiny HP pool.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom, Dawnbreaker. However, this also means they are easily stunned.
Axe
* Huskar is often played at low health to maximize the bonuses from 
Berserker's Blood, and also because his abilities cost health to use. This makes him especially vulnerable to Culling Blade.
* Berserker's Blood gives Huskar no protection against the pure damage of Culling Blade. Its attack speed bonus also means that Counter Helix will proc more often.
* Axe's tankiness and base health regeneration makes it hard for Huskar to take him down with 
Burning Spears.
Additional:
* Berserker's Call and Blade Mail can be used immediately after Huskar jumps on Axe with Life Break.
* Huskar's high attack speed procs Counter Helix repeatedly.
* Huskar's health loss from using his abilities make him a frequent target for Culling Blade.
Nyx Assassin
* Nyx Assassin can reflect Life Break with Spiked Carapace.
Axe
* False Promise will not save an ally from Culling Blade if their health is low enough.
* Fate's Edict, offensively or defensively, does little to protect Oracle's allies from the majority of Axe's damage.
Axe
* Heroes with other kind of disables that pierce spell immunity can hold Pangolier in place during Rolling Thunder: Axe, Beastmaster, Enigma, 
Magnus, Pudge, Batrider, Bane, Winter Wyvern
Axe
* Durable heroes can stand against Tusk during 1v1: Axe, Dragon Knight, 
Night Stalker, Centaur Warrunner, Wraith King and more.
Axe
* Heroes that can keep Monkey King stunned for a long time can pose a threat: Axe, Centaur Warrunner.
Nyx Assassin
* Heroes that can pick you off: Clinkz, Nyx Assassin, 
Puck, Riki.
Axe
* Heroes with burst damage of their own won't be afraid to go toe to toe with Void Spirit, like Ursa, 
Lifestealer, or Axe.
Axe
* Heroes who can continue dealing damage even while being stunned: Luna, 
Razor, Axe, Bristleback, Leshrac, Death Prophet.
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.
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.
Axe
* 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.
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.
Axe
* Culling Blade's instant kill is not prevented by Borrowed Time should Abaddon's health falls below the threshold.
Additional:
* Culling Blade ignores 
Borrowed Time should Abaddon's health falls under the threshold.
* 
Aphotic Shield does nothing against Berserkers Call and has to be used constantly to remove the very small mana cost of Battle Hunger in lane.
Nyx Assassin
* Nyx Assassin might not kill Abaddon with his nuke, but a support Abaddon will struggle to protect an ally from him.
Axe
* Melee heroes who rely on summons, illusions, or clones will trigger Counter Helix more often, thus taking more damage: Meepo, Lycan, Phantom Lancer
Additional:
* The combination of Counter Helix and Berserker's Call can disable multiple Meepos and deal heavy area damage.
* Axe's natural high survivability makes it difficult to burst him down with Poof or chip away at his health with Ransack.
Axe
* Heroes who can stop Axe from getting close will severely inhibit his presence in fights: Bristleback, Crystal Maiden, Batrider, Arc Warden, Winter Wyvern, Clockwerk
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
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: 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.
Axe
* Heroes who can stop Axe from getting close will severely inhibit his presence in fights: Bristleback, Crystal Maiden, Batrider, Arc Warden, Winter Wyvern, Clockwerk
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.
Nyx Assassin
* Heroes who rely on damage over time as Spiked Carapace can block and reflect only one instance of damage: 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
* 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.
Axe
* Berseker's Call catches Slark in 
Shadow Dance, wasting its duration and preventing him from escaping to regenerate.
* Unlike most disables, Dark Pact cannot dispel Berserker's Call and the output damage would be returned by Blade Mail.
Additional:
* Berserker's Call forces Slark to attack him, even during Shadow Dance.
* Counter Helix will hit Slark in Shadow Dance. It will also trigger frequently against Slark's high attack speed provided by Essence Shift stacks.
* Culling Blade finishes off Slark before he gets a chance to slip away and regenerate his health, preventing him from playing his typical hit-and-run style.
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.
* The mana burn from Vendetta also prevents Lina from casting her full combo.
* 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.
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.
Axe
* Troll Warlord's high attack speed means Counter Helix will proc extremely frequently even without creeps near him. This, combined with a Blade Mail means Axe can easily solo kill Troll Warlord even in later stages of the game.
* 
Battle Trance does not save Troll Warlord from a Culling Blade.
Additional:
* Troll Warlord has significant attack speed due to Fervor and Battle Trance, giving Axe a higher chance to proc Counter Helix and seriously injure Troll Warlord due to his relatively low maximum health.
* Axe often purchases Blade Mail, which can help Axe turn Troll Warlord's farm and high physical damage against him. The bonus armor provided by Berserker's Call means that Troll Warlord will take a lot more damage than Axe.
* Culling Blade is still capable of killing Troll Warlord during Battle Trance if his HP is low enough.
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.
Axe
* Berserker's Call catches Phantom Lancer when he is hidden among his illusions.
* Counter Helix quickly destroys Phantom Lancer's illusion army. The more illusions there are, the more often Counter Helix is triggered.
* Phantom Lancer's low early game health makes him an easy target for Culling Blade.
Additional:
* Berserker's Call helps locking down Phantom Lancer in a group of illusions.
* Counter Helix combined with Blade Mail clears Phantom Lancer's illusions quickly.
* Phantom Lancer's low health in the early game makes him a frequent target for Culling Blade.
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.
Axe
* Axe will destroy her illusions by proccing Counter Helix more often due to him being hit by more attacks.
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
Axe
* Berserker's Call prevents Anti-Mage from escaping with Blink, and works well with Blade Mail against Anti-Mage's relatively low health.
* Counter Helix often triggers even if Axe's depleted of mana, which will make Anti-Mage take more damage than he's dealing and deals pure damage, ignoring the protection from Counterspell.
* Axe's low mana pool makes him a bad target for using Mana Void.
* Axe's high base health regeneration allows him to dominate the lane against Anti-Mage, especially with a support.
Additional:
* Berserker's Call is one of the most reliable ways to lock down Anti-Mage, preventing him from 
Blinking away.
* Anti-Mage's high attack speed, along with illusions from Manta Style, triggers Counter Helix continuously.
* Axe's low mana pool and high health pool make 
Mana Void deal very little damage to Axe.
Nyx Assassin
* Heroes with very little to no area-of-effect abilities will struggle greatly against Broodmother: Sniper, Phantom Assassin, Nyx Assassin, Bane, Visage, Bounty Hunter.
Axe
* Berserker's Call can catch Broodmother in her web, as well as groups of spiderlings. This is particularly effective when Broodmother attempts to push towers with her spiderlings.
* Counter Helix destroys spiderlings very quickly and earns Axe a good deal of gold.
Additional:
* Berserker's Call forces Broodmother and her spiderlings to attack, allowing for large amounts of pure damage to be done through Counter Helix.
Axe
* Heroes who can stop Axe from getting close will severely inhibit his presence in fights: Bristleback, Crystal Maiden, Batrider, Arc Warden, Winter Wyvern, Clockwerk
Axe
* Magnetic Field doesn't provide a protection against Berserker's Call and Counter Helix and his high attack speed together with Tempest Double will often trigger Counter Helix.
* The threat of a blink and Berserker's Call may make the real Arc Warden stay further back, thus effectively halving the team's damage output for a while.
Axe
* Enigma can be a perfect counter-initiator with his ultimate. A perfectly timed Black Hole will turn the tide of any initiation, especially from heroes like; Spirit Breaker, Legion Commander, Axe, Puck, and Slardar.
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.
Axe
* Long ranged disables, especially those that pierce spell immunity, cancel Black Hole: Beastmaster's 
Primal Roar, Bane's 
Fiend's Grip, Faceless Void's 
Chronosphere, Magnus's 
Reverse Polarity, Axe's Berserker's Call, Pudge's
Meat Hook.
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.
Axe
* Heroes who can stop Axe from getting close will severely inhibit his presence in fights: Bristleback, Crystal Maiden, Batrider, Arc Warden, Winter Wyvern, Clockwerk
Axe
* Axe forces Bristleback to turn around with Berserker's Call, allowing allies to attack him without fear of his passive.
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, although he can at least partially counter it with a well-timed Spiked Carapace.
* 
Thirst is always a threat to Nyx Assassin, hindering his attempt of escape using Vendetta.
* 
Rupture also prevents Nyx Assassin from escaping with Vendetta, as it forces him to stay still.
Axe
* Heroes with high armor and durability can be exceptionally hard for Bloodseeker to bring down: Dragon Knight, Axe
Axe
* Long lockdown is a great way to deal with Axe to prevent Berserker's Call from being used, heroes such as Legion Commander, Beastmaster and Primal Beast are good examples of this.
Additional:
* Berserker's Call will be a stun for Primal Beast and not much else due to Trample making him unable to attack.
* Battle Hunger is neglitable because Primal Beast has a much bigger health than Axe, so he does not need to fear being slowed, or his other abilities including Counter Helix or even a Blade Mail.
* Getting Primal Beast low enough to use a successful Culling Blade can be very difficult due to his massive health advantage over most heroes.
* Not ability related but Primal Beast does not need to fear Axe in lane, as Trample, combined with Uproar and Onslaught will do a ton of damage even if Axe has a 
Vanguard.
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.
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.
Axe
* Heroes with gap-closing abilities will be easy targets for Berserker's Call: Phantom Assassin, Faceless Void, Slark, Chaos Knight, Morphling, Queen of Pain
Axe
* 
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.
Nyx Assassin
* Spiked Carapace reacts on any of the damage over time from Phoenix's abilities and can interrupt Sun Ray and Icarus Dive.
Axe
* 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 stops Axe's game plan of using Berserker's Call multiple times and since he's in the middle of the fight, this spell is very easy to grab kills onto him.
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 if Axe's health is low enough.
* Heartstopper Aura can be very effective against Axe due to Axe's high strength gain.
* However, bear in mind that Berserker's Call can prevent Necrophos from using his Ghost Shroud to defend his fragile self from physical damages. And Heartstopper Aura can unintentionally help Axe to trigger his Counter Helix more frequently while also hurting Necrophos with Blade Mail during activation.
* Nonetheless Heartstopper Aura is not considered as a normal attack, thus it will not trigger Counter Helix, so anyone who wrote the statement above should be awarded with MVP and considered a TI champion purely for the innovation of new mechanics.
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.
Axe
* 
Decrepify can be used on allies to prevent them from attacking Axe and triggering Counter Helix during Berserker's Call. He can also cast it on Axe to prevent anyone from attacking him.
* 
Life Drain can be used to heal himself or allies caught in Berserker's Call, preventing them from dropping low enough for Axe to kill them with Culling Blade.
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.
Axe
* Outworld Destroyer's pure and magical damage is particularly effective against Axe.
* 
Astral Imprisonment is an excellent way to defend against an initiating Axe.
* 
Sanity's Eclipse deals high damage to Axe due to his low mana pool.
Additional:
* Berserker's Call bonus armor doesn't block Arcane Orb's pure damage.
* Astral Imprisonment can be used to prevent an ally or Outworld Destroyer himself from an Axe initiation.
* Axe's low mana means he's susceptible to a powerful Sanity's Eclipse.
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
* 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.
Axe
* Axe can Berserker's Call into a flock of Familiars, proccing Counter Helix and killing them off.
* Familiars' very fast attacks will proc Counter Helix, receiving full damage due to their low attack range.
Axe
* Feast makes it impossible to for Lifestealer to be culled with
Culling Blade and also deals high damage to Axe due to his naturally high health. However, Rage can still be pierced by 
Berserker's Call and 
Counter Helix.
Nyx Assassin
* Like with Juggernaut's
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.
*
*
* Like with Juggernaut, any attempt for Nyx Assassin to gank and kill Lifestealer will hurt Nyx Assassin more than Lifestealer.