* If Ursa uses Enrage, Pugna's Life Drain is next to worthless against him, due to Ursa taking 80% less damage, therefor Pugna heals by only 20% of the damage that the spell deals.
* If Ursa jumps on you with a Blink Dagger he can easily wipe you out with Overpower.
* Ursa's Overpower can destroy a full health Nether Ward and still have a few swipes leftover, Also Ursa's low mana spells means he takes negligible damage from the Nether ward anyway.

* 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. Mana Burn 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.
Additional:
* 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.

* Ursa can deal lots of damage during the laning phase before Terrorblade can have Sunder available.
* Even if Terrorblade succeeds to use Sunder on Ursa, Enrage's damage reduction can help Ursa survive after Terrorblade has used Sunder him while also making Terrorblade's attacks tickle, even during Metamorphosis for it's duration.

* Nyx Assassin deals large amounts of pure damage with Vendetta and magical damage with Impale and Mana Burn, 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.
* Mana Burn might drain too much mana for Terrorblade to be able to use Sunder if he isn't careful in the early to mid game.

* Enrage with Aghanim's Scepter can dispel Flaming Lasso.

* 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.

* Ursa can do damage very fast with his Overpower and Fury Swipes abilities, Necrohops will have taken large amounts of damage before he can use Ghost Shroud, And if Ursa has Skull Basher, Ursa will quickly demolish Necrophos before he can do anything to retaliate.
* Skilled and smart Ursa can bait Necrophos into using Reaper's Scythe on him, and with his Aghanim's Scepter upgraded Enrage that can negate 80% of the damage, Ursa will often survive and waste Reaper's Scythe.

* 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 Mana Burn or Impale.

* 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.
Additional:
* Level 4 Mana Burn burns of Medusa's mana every 5 seconds if Medusa only increases her mana pool with intelligence. Additionally, 70% of the Mana Burn damage gets mitigated by Mana Shield, burning even more mana.
* 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.

* Medusa's tankiness doesn't help her very much against Fury Swipes in long teamfights.
* With no escape mechanism and a slow movement speed, getting jumped on by Ursa usually spells a quick end for Medusa in the early game.
Additional:
* Ursa's status resistance from Enrage reduces Medusa's gaze.
* Ursa can stack damage with Fury Swipes easily against her Mana Shield in a prolonged team match.

* Mana Burn does tons of damage against Lina because of her high intelligence. The mana burn 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.

* Light Strike Array has a long delay, making her vulnerable for Ursa's burst.
* Enrage can protect Ursa against Lina's high magical burst.

* Spiked Carapace reacts on any of the damage over time from Phoenix's abilities and can interrupt Sun Ray and Icarus Dive.

* Ursa can easily unleash a number of attacks in an incredibly short amount of time, easily destroying the Supernova in a couple of seconds regardless of Fire Spirits' debuff. His Enrage also dampens any damage Phoenix might toss at his direction, as well as remove any debuffs Phoenix may place on him.

* Mana Burn drains Pudge's little mana which may render Meat Hook and Dismember unusable.
* 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.

* Low armor and lack of escape makes Pudge vulnerable to Ursa, specially when he gets his Blink Dagger.
* If Pudge lands a Meat Hook on Ursa, Ursa can simply face Pudge head on provided he can burst him down before any follow up disables.
* Enrage's Aghanim's Scepter upgrade allows Ursa to dispel Pudge's Dismember.

* Fury Swipes will keep stacking on Tidehunter since it cannot be dispelled by Kraken Shell and its bonus damage cannot be reduced by Anchor Smash.
* Enrage dispels the slow from Gush, and if upgraded with Aghanim's Scepter, can even dispel Ravage's stun.

* Mana Burn can instantly deplete Tidehunter's low mana pool, especially in the early game, potentially preventing Tidehunter from casting Ravage.
* Ravage's travel time allows Nyx Assassin to easily stun Tidehunter with Spiked Carapace.

* 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 Mana Burn will deal increasing damage for each point of intelligence Silencer has stolen, turning Silencer's intelligence steal against him.

* Silencer relies on preventing enemies from using abilities in teamfights with Arcane Curse, Last Word, and Global Silence. However, they are ineffective against Ursa since he relies more on items and attacks than abilities.
* Against a carry Silencer, Enrage can help Ursa reduce all damage he takes, even Glaives of Wisdom's pure damage will just tickle Ursa while his Enrage is active.

* Heroes with high burst damage: Lina, Lion, Luna, Nyx Assassin, Queen of Pain.

* Earthshock prevents Shadow Fiend from escaping after Ursa used his Blink Dagger to get on top of him.
* Overpower and Fury Swipes allow Ursa to quickly kill Shadow Fiend.
* Enrage keeps Ursa alive in a manfight with Shadow Fiend and allows him to stay close, even if Shadow Fiend uses Requiem of Souls.

* Ursa can shred Warlock's Golems in a few seconds with Fury Swipes and Overpower.

* 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.

* Jumping on Ursa with Life Break is often suicide for Huskar, as he will be immediately bursted down with Fury Swipes.
Additional:
* Huskar likes fights with a long duration and is usually at low health, making him vulnerable against Ursa's physical damage.
* Jumping in with Life Break against Ursa is suicide, as Enrage, Overpower, and Fury Swipes will easily shred Huskar.

* Nyx Assassin can reflect Life Break with Spiked Carapace.

* 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.

* Enigma lack burst damage, and that makes him vulnerable to heroes who can recover themselves and turn the fight around to their advantage after Enigma finishes his initiation: Faceless Void, Terrorblade, Ursa, Weaver, Broodmother, Slark, Abaddon, Wraith King, Lifestealer.

* Timbersaw's physical survivability revolves around Reactive Armor, which is largely ignored by Fury Swipes due to the extreme amounts of damage it does in a very few number of attacks.
* Timbersaw's burst damage will not do much against Enrage, although he could easily use Timber Chain to escape, wasting the duration of it.

* 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.

* Ursa's massive physical damage can destroy Kunkka quickly.
* Enrage can be activated before being hit by Ghostship to prevent most of the damage.
* Earthshock slows Kunkka's movement speed. With no escape abilities, Kunkka is easy prey.

* Spiked Carapace stops Snapfire's Mortimer Kisses.

* 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.

* 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.

* Nyx Assassin takes advantage of Invoker's massive intelligence gain and mana pool to do tons of damage using Mana Burn, as the spell does more damage based on the target's intelligence.
* Nyx Assassin can simply activate Spiked Carapace while under many Invoker's abilities to stun him.

* Spiked Carapace can be easily triggered by Flame Guard or Battle Fury, setting up a deadly Impale.
Additional:
* 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.
* Mana Burn is also good, as Ember Spirit relies on his limited mana pool for the early to midgame.

* Fury Swipes does not work on allies, mitigating a majority of Ursa's damage.
* Ursa's unimpressive attack speed and attack damage without Overpower and Fury Swipes means that he deals little to no damage to allies.
* Aghanim's Scepter upgraded Enrage allows Ursa to survive Winter Wyvern's initiation.

* 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.

* Enrage will make it very difficult to burst him down.
* Zeus has little armor, HP and mobility; Ursa's favorite kind of target.

* Spiked Carapace can stop Dawnbreaker's Solar Guardian which will eliminate her global presence and limits her movement around the map.

* 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 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:
* Spike 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.

* Vendetta disables Vengeance Aura and allows him to attack Vengeful Spirit with Impale and Mana Burn.
* Spiked Carapace is easy to use against a Wave of Terror or Magic Missile.

* Nyx Assassin's Spiked Carapace will stun Leshrac when hit by any of his AOE abilities.
* Mana Burn deals high damage due to Leshrac's high intelligence gain and burns a large amount of Leshrac's essential mana pool.

* Nyx Assassin has a lot of burst damage from his Impale, Mana Burn, 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.

* His whole skillset acts like a counter to Tinker:
* Impale prevents Tinker from blinding Nyx Assassin or fighting back, while giving Nyx' allies time to catch up to Tinker's position.
* Mana Burn 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.
Additional:
* March of the Machines and 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.

* Heroes with invisibility: (Riki, Clinkz, Nyx Assassin

* Large area-of-effect with delay or require channeling: Enigma, Crystal Maiden, Invoker, Shadow Fiend, Pugna, Keeper of the Light
* The nature of some abilities turn them into an easy target for a turnover from Spiked Carapace:
* Slow-moving projectiles: Skywrath Mage, Tinker, Necrophos
* Large area-of-effect with delay or require channeling: Enigma, Crystal Maiden, Invoker, Shadow Fiend, Pugna, Keeper of the Light
* Deals damage over time: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom

Additional:
* 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.
* However, Mana Burn's Mana Burn can be more or less mitigated with Chakra Magic.

* Heroes without an escape mechanism: Shadow Fiend, Alchemist

Additional:
* Chemical Rage will rarely save Alchemist against Ursa's Fury Swipes.
* Enrage allows Ursa to both be a threat to Alchemist and avoid his over time damage.

* Heroes with burst damage of their own won't be afraid to go toe to toe with Void Spirit, like Ursa, Lifestealer, or Axe.

* Ursa is a special mention because despite Bulwark diminishing most of the damage Ursa does, he is quite durable, especially with Enrage, discouraging the aggressive all-in playstyle of Mars; Ursa can simply not target Mars.

* Due to Tiny's non-existent agility gain, high physical damage heroes are more effective against him (Clinkz, Templar Assassin, Ursa, Wraith King etc).

* Deals damage over time: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom
* The nature of some abilities turn them into an easy target for a turnover from Spiked Carapace:
* Slow-moving projectiles: Skywrath Mage, Tinker, Necrophos
* Large area-of-effect with delay or require channeling: Enigma, Crystal Maiden, Invoker, Shadow Fiend, Pugna, Keeper of the Light
* Deals damage over time: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom

* 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.

* All assassin-type carries in a one against one situation: Meepo, Phantom Assassin, Riki, Ursa. Luna's only chances are that she buys Ethereal Blade or Black King Bar to gain a slight edge against them, or both items if necessary.

* Deals damage over time: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom
* The nature of some abilities turn them into an easy target for a turnover from Spiked Carapace:
* Slow-moving projectiles: Skywrath Mage, Tinker, Necrophos
* Large area-of-effect with delay or require channeling: Enigma, Crystal Maiden, Invoker, Shadow Fiend, Pugna, Keeper of the Light
* Deals damage over time: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom

* Slow-moving projectiles: Skywrath Mage, Tinker, Necrophos
* The nature of some abilities turn them into an easy target for a turnover from Spiked Carapace:
* Slow-moving projectiles: Skywrath Mage, Tinker, Necrophos
* Large area-of-effect with delay or require channeling: Enigma, Crystal Maiden, Invoker, Shadow Fiend, Pugna, Keeper of the Light
* Deals damage over time: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom

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.
* Mana Burn is annoying at all stages of the game as it turns Skywrath Mage's high intelligence growth against him.
* Spiked Carapace gives Nyx some degree of protection against Skywrath's spells.

* Nyx Assassin, Bounty Hunter and Slark can all sneak up and kill you, Nyx being particularly deadly. Watch Slark carefully, as he can break either (but not both unless you are making a mistake) of your 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 you from prey to predator.

* Heroes with damage burst can often kill Chen or his allies before he can use Hand of God: Lina, Techies, Shadow Fiend, Pugna, Nyx Assassin.

* 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 Mana Burn that much more deadly against Puck.
* An ill-timed Phase Shift can turn into an easy setup for Impale.
Additional:
* 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.

* 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.

* Ursa's high physical burst damage combined with his big attack speed and durability makes him a very bad target for Power Cogs.
* Even with Blade Mail, Ursa's Enrage will negate most of the reflected damage.

* Outworld Destroyer's high mana pool, high intelligence, and makes him a prime target for Mana Burn.
* 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.
Additional:
* 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 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.

* Fury Swipes damage is not reduced by Atrophy Aura, essentially bypassing Underlord's only natural defense.
* Enrage can quickly dispel the root of Pit of Malice.

* Vendetta breaks Untouchable and deals great damage against her.
* Enchantress' lack of mobility makes her a primary target for ganking with Vendetta.
* Spiked Carapace can reflect Impetus and stun Enchantress.
* Mana Burn can deal tremendous damage against her due to being an Intelligence hero.
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.

* 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 gains an item advantage: Lina, Necrophos, Nyx Assassin, Gyrocopter. Should be noted these heroes are usually quite squishy and don't scale well with health. So to some respect, they are on a time crunch.

* Fury swipes can tear Dragon knight down as it stacks infinitely.

* Mana Burn 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.
Additional:
* Mana Burn removes much-needed mana for Ball Lightning.
* Spiked Carapace triggers on Static Remnant for an easy stun.

* Many of Nyx Assassin's abilities are good against Windranger.
* Impale is great for stunning Windranger and allowing additional disables to be landed.
* Mana Burn is useful against Windranger's decent intelligence growth and also burns some mana, preventing her from using more abilities.
* 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.

* Deals damage over time: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom
* The nature of some abilities turn them into an easy target for a turnover from Spiked Carapace:
* Slow-moving projectiles: Skywrath Mage, Tinker, Necrophos
* Large area-of-effect with delay or require channeling: Enigma, Crystal Maiden, Invoker, Shadow Fiend, Pugna, Keeper of the Light
* Deals damage over time: Venomancer, Huskar, Ember Spirit, Dark Seer, Sand King, Doom

* 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.

* Heroes that can pick you off: Clinkz, Nyx Assassin, Puck, Riki.

* Fury Swipes is not protected by Blade Fury and allows Ursa to harass Juggernaut anytime.
* Enrage reduces the damage taken from Omnislash.

* Heroes who can drain mana can make Omniknight useless after he uses one or two abilities: Lion, Anti-Mage, Nyx Assassin