* Lycan's wolves deal little damage to Bristleback, and are easily killed by Quill Spray, even when they're invisible.
* Lycan's lack of burst damage makes it very hard for him to kill Bristleback, especially when his back is turned.
Additional:
* Quill Spray can be used to kill Lycan's summons.
* Bristleback allows him to stay alive against Lycan while dishing out counter attacks
* He can overpower Lycan with his Warpath instead.

* Rupture completely negates Lycan's high mobility.
* All of Lycan's summons are good sources of healing with Bloodrage.
Additional:
* Rupture completely negates Lycan's high mobility.
* All of Lycan's summons are good sources of healing with Bloodrage.

* Every Meepo clone adds to Thirst's bonuses.
* Bloodseeker can chase down retreating clones when Meepo tries to cycle weaker clones away from combat.

* Quill Spray usually hits Meepo's clones, although Bristleback cannot turn his back when rooted with Earthbind.

* Quill Spray is very effective against Io, as it has very low armor and has to stay close to the fight to not break its Tether.

* Thirst allows Bloodseeker to see where Io relocated to, should either Io or the tethered hero have low health.
* Rupture forces Io to stay in place, preventing it from using the Tether bonus movement speed to escape.

* Thirst detects Riki whenever his health is low.
* Rupture does large damage when Riki uses Blink Strike.

* The bonus Backstab damage from Cloak and Dagger is rendered irrelevant with Bristleback and hurts Riki more than him because of the passive Quill Spray.
* Riki still gets damaged by Bristleback's Quill Spray while invisible, and it can be hard to deal with in lane.
* Bristleback is not too bothered by Smoke Screen. Though he cannot use Quill Spray manually inside it, it still procs passively when he takes damage from the back. The movement speed from Warpath allows him to get out of the area easily.
* Due to Bristleback's natural tankiness, he is an ideal Gem of True Sight carrier.
* Riki rarely buys Silver Edge to break Bristleback's passive because the invisibility aspect of it is redundant.
Additional:
* Quill Spray will hit Riki even when he is invisible.
* Cloak and Dagger's bonus backstab damage is rendered irrelevant against Bristleback.
* Smoke Screen does not stop Bristleback's passive from activating.
* Due to Bristleback's natural tankiness, he is an ideal Gem of True Sight carrier, directly countering Riki's invisibility.

* Huskar is often at low health, providing large Thirst bonuses to Bloodseeker.
* Life Break can trigger Rupture's damage.
* A self applied Bloodrage together with Blademail means it's almost suicidal for Huskar to jump on Bloodseeker with Life Break
Additional:
* Huskar is often at low health, providing large Thirst bonuses.
* Life Break triggers Rupture's damage.

* Bristleback's tankiness and Bristleback allow him to outlast Burning Spears' damage-over-time at almost any point in the game. In addition, if Huskar chooses to cast Life Break on Bristleback, Bristleback can simply turn around before it hits and receive little damage.
* Viscous Nasal Goo will reduce Huskar's low armor even further, and Quill Spray and Warpath will tear him down extremely quickly.
Additional:
* The damage from Burning Spear can be reduced by turning away from Huskar.
* Bristleback can bait Huskar into using Life Break on him, then turn around and receive very little damage.

* Blood Rite can flush Enigma out of position and potentially force him to activate his spell immunity prematurely, before pulling off a Black Hole combo.
* Bloodseeker can find an Enigma out of position and Rupture him, making it difficult to initiate properly in a team fight, as it pierces through Black King Bar

* Bristleback's tankiness can enable him to chase Enigma out of a teamfight, making it difficult to initiate with a Black Hole.

* Heroes with good mobility to avoid Jakiro's abilities and with good chase to punish Jakiro from pushing a tower: Bloodseeker, Ember Spirit, Juggernaut, Phantom Assassin, Weaver.

* Macropyre's frequent damage ticks causes Bristleback to activate repeatedly, resulting in free damage as long as Bristleback faces away from Jakiro.

* Bloodseeker's Rupture can turn Bounty Hunter's mobility against him, and prevents him from escaping with Shadow Walk due to the potentially heavy damage.
* Thirst can prevent Bounty Hunter from escaping with Shadow Walk should Bounty Hunter's health become low enough.

* Bristleback's Viscous Nasal Goo can catch and slow Bounty Hunter. Warpath and Quill Spray can defeat him quickly due to his small HP pool when compared to Bristleback's.

* Heroes who continue dealing damage while being stunned: Luna, Razor, Axe, Bristleback, Leshrac,

* Heroes with fast movement abilities will suffer huge damage when afflicted by Rupture: Spirit Breaker, Earth Spirit, Dark Seer.

* Sniper is suspectible to being ganked by Bloodseeker, who can easily kill Sniper due to his lack of mobility and escape mechanisms.
* Even if Sniper builds mobility items, Bloodseeker can prevent and even punish Sniper from/for using them with Rupture; Sniper is forced to stand still with Shadow Blade, while Hurricane Pike and Blink Dagger deals damage if he attempts to use them while Ruptured.
Additional:
* Sniper's lack of mobility and escape mechanisms makes him one of the easier heroes for Bloodseeker to gank.

* Bristleback's tankiness and damage reduction from the rear makes him very hard for Phantom Lancer to chase and finish off, due to his lack of burst damage.
* Quill Spray destroys Phantom Lancer's illusions.
* Bristleback's passive costs no mana, meaning that it will continue to trigger even if Phantom Lancer drains Bristleback's mana with Diffusal Blade.
Additional:
* Quill Spray cleans up Phantom Lancer's illusions in no time.
* Phantom Lancer's complete lack of burst damage makes it nearly impossible for him to kill Bristleback during chases.

* Bloodseeker's Rupture shows a clear red trail effect on the real Phantom Lancer.
* Heroes with undispellable debuffs will help identify the real Phantom Lancer through visual effects or debuff indicators, provided that it was cast on the real Phantom Lancer to begin with:
* Doom's Doom marks Phantom Lancer with a highly visible effect, and also silences him.
* Bloodseeker's Rupture shows a clear red trail effect on the real Phantom Lancer.
* Ancient Apparition's Ice Blast will only debuff Phantom Lancer and not his illusions.
* Grimstroke's Soulbind is undispellable.
* Shadow Demon's Demonic Purge is undispellable.
* Monkey King's Jingu Mastery is undispellable and puts a big yellow Mark over his head.

* Thirst prevents Slark from healing with Shadow Dance.
* Rupture will deal damage during Pounce.
* Dark Pact cannot dispel Rupture, preventing Slark from escaping ganks.
Additional:
* Thirst makes Slark visible while at low health, canceling out Shadow Dance's passive. For this reason, Bloodseeker is usually considered the hardest counter to Slark.
* Rupture cannot be dispelled by Dark Pact, and using Pounce while affected by it will cause Slark to take damage.

* Bristleback decreases Tiny's high burst damage against Bristleback.
* Tiny's high damage will also proc Bristleback multiple times.
* Viscous Nasal Goo can help counteract the bonus armor granted by Grow.

* Bristleback's abilities are nearly useless for Rubick to Spell Steal, as he does not gain the bonuses from Warpath.
Additional:
* Rubick deals little damage on his own, so Bristleback can simply shrug off all his spells and chase you down with his spells and attacks.
* Quill Spray requires multiple casts and close range to add up stacks. Because Rubick does not stay in the front lines, it's generally not a good spell for him to steal.
* Viscous Nasal Goo will slow Rubick down even further and reduce his armor, making him vulnerable to Quill Spray and the damage bonus from Warpath.

* Thirst provides constant sight and speed to Bloodseeker, allows him to catch up a fleeing Pangolier through all of his mobility.
* Rupture is a great threat to Pangolier, causes him to take heavy damage if he uses Swashbuckle and especially Rolling Thunder, forcing him to stop his ultimate prematurely, or keep rolling to his death.
Additional:
* Rupture works through Rolling Thunder and Swashbuckle, greatly reducing Pangolier's mobility.

* Blood Rite prevents Queen of Pain from escaping with Blink.
* Blink will trigger the extra damage from Rupture.
Additional:
* Bloodrage is the best tool to pop her spell block talent or her Linken's Sphere, following up with Rupture.
* Blood Rite silences her, preventing her from initiating or escaping.
* With Thirst, even if she Blinks away, Bloodseeker can catch right up to her.
* Rupture will heavily damage Queen of Pain if she tries to Blink away.
* She is, however, one of the few heroes who can avoid the damage from Rupture if she does it correctly.

* Quill Spray will hit Sand King inside Sand Storm, damaging him and putting Sand King's Blink Dagger on cooldown, preventing him from escaping.
* Epicenter's numerous damage ticks will trigger Bristleback's passive repeatedly during teamfights.

* Rupture turns Windranger's mobility against her.
Additional:
* Windrun triggers the damage from Rupture.

* Rupture will fully damage Void Spirit during his ultimate, removing his main escape mechanic during fights and his way to disrupt them heavily.
* Blood Rite will force Void Spirit to use Dissimilate or Astral Step or be silenced. In the latter's case, it can be dangerous when combined with Rupture.

* Rupture deals extra damage to Magnus during Skewer or Force Staff, preventing him from escaping or counter-initiating, forcing him to invest on a Linken's Sphere.

* Fortune's End cannot dispel Warpath stacks on Bristleback or Quill Spray stacks on allies.
* Bristleback can heavily reduce Oracle's damage output. With it, Oracle may accidentally heal Bristleback with Purifying Flames, especially if Bristleback has bonus magic resistance.

* Quill Spray and Bristleback harass Luna more efficiently than she does with Lucent Beam.
* Bristleback withstands Luna’s nukes, and gives lots of damage in return.
* Viscous Nasal Goo and Warpath are enough to outrun a speedy Luna.
* Bristleback tends to be a frequent carrier of Crimson Guard, which is good protection from bouncing glaives.
Additional:
* Multiple instances of damage from Eclipse will trigger Bristleback's passive repeatedly in a short time, dealing tremendous damage to Luna and her teammates.
* Luna's damage burst may be high, but it will not be enough for her to take down Bristleback.

* Blood Rite can silence Warlock, which as a spellcaster is bad for him.
* Rupture prevents Warlock from moving without taking damage, which due to his general lack of escapes is bad for him, and when combined with Blood Rite can be a very lethal combo.

* Viscous Nasal Goo can hinder Crystal Maiden's already abysmal mobility, which allows Bristleback (or his teammates) to run her down and kill her.
* Bristleback frequently builds Blade Mail, which can quickly kill Crystal Maiden if her ultimate is used while he is under its effect.
* The passive part of Bristleback will trigger many, many times under the damage from Freezing Field, and as the stacks increase, the damage output from each successive cast (or proc) will eat away at Crystal Maiden's small HP pool.

* Lone Druid and The Spirit Bear cannot burst down Bristleback due to Bristleback
* Bristleback can easily run to Lone Druid without any hesitation, with Viscous Nasal Goo to reduce armor and slow the Spirit Bear or Lone Druid and Quill Spray can deal damage to both Lone Druid and the Spirit Bear at the same time

* Nether Swap triggers extra damage from Rupture.
* Blood Rite sets up while Vengeful Spirit using her Nether Swap within a timed correctly.

* Rupture can quickly kill Mirana if she tries to Leap away.
* Thirst detects Mirana and her allies during Moonlight Shadow.
Additional:
* Thirst detects Mirana or her ally at low health during Moonlight Shadow.
* Rupture deals high damage when Mirana uses Leap.

* Skeleton Walk is not enough to outrun Bloodseeker, and is detected by Thirst.
Additional:
* Thirst reveals Clinkz if he tries to escape with Skeleton Walk with low health. It also allows Bloodseeker to match or exceed Clinkz's speed.
* Rupture negates the mobility provided by Skeleton Walk in any attempt to escape or reposition in fights.
* Bloodseeker can easily build items to counter Clinkz, including Talisman of Evasion upgrades, Blade Mail, and armor items.

* Quill Spray destroys spiderlings, and hits Broodmother even when she's regenerating in her webs. This makes Bristleback one of her hardest counters in lane.
Additional:
* Bristleback reduces most of Broodmother's and her spiderlings' damage.
* Quill Spray will hit any spiders in its proximity, hindering Broodmother's fighting and farming capabilities.

* Heroes that have AoE damage: Lina, Keeper of the Light, Timbersaw, Leshrac, Bristleback, Axe

* Heroes that can maintain vision on Monkey King can see when he uses Tree Dance: Bloodseeker, Treant Protector with Eyes In The Forest, Sniper, Weaver

* Heroes with silences : Bloodseeker, Riki, Silencer.

* Heroes with long-lasting, undispellable debuffs will pinpoint the true Naga Siren: Spirit Breaker, Bloodseeker.

* Heroes with high physical damage can damage Lifestealer more than he can heal: Bristleback, Clinkz, Luna,Shadow Fiend, Slardar

* Heroes with fast movement abilities will suffer huge damage when afflicted by Rupture: Spirit Breaker, Earth Spirit, Dark Seer.

* 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.

* Heroes with fast movement abilities will suffer huge damage when afflicted by Rupture: Spirit Breaker, Earth Spirit, Dark Seer.

Additional:
* Rupture can deal a lot of damage to either a surged Dark Seer or his allies and prevent the target to get into position.

* Heroes with damage-over-time abilities will not only proc Bristleback's passive continuously, they will also do little harm to him when he is facing away from the source: Venomancer, Arc Warden

* 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.

* 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.

* Bloodseeker's Rupture turns Night Stalker mobility against him and Thirst grants movement speed bonus and vision prevents Night Stalker from initiating and re-initiating.

* As a spellcaster, silences will nullify him entirely. Some notable examples are Death Prophet, Drow Ranger, Bloodseeker, Disruptor and many others.
* Doom, as usual, fits this description nicely.

* Although Blood Rite can be easily avoided, if it does hit, its lengthy silence and pure damage can be a severe punishment for a slow, unobservant, or simply unfortunate Phoenix. His Rupture can turn Icarus Dive into a suicide option, and it cannot be dispelled, meaning even if Phoenix completes a Supernova, choosing to Dive may just cut its health back down. And finally, due to Phoenix's health costs, too much careless ability spamming may just put Phoenix into Bloodseeker's vision, making it a very tempting ganking target.
Additional:
* Phoenix expends health to use its abilities, making it a good target for Thirst.
* Rupture deals heavy damage against Icarus Dive.

* Bristleback need not worry about charging into Magnetic Field, and quickly clearing up Arc Warden's summons and Tempest Double with Quill Spray.
Additional:
* Bristleback activates frequently while he escapes from Arc Warden's Necronomicon army.
* Arc Warden has little armor and mobility, which makes him an easy target to apply Quill Spray and Viscous Nasal Goo stacks.

* Quill Spray quickly destroys Chaos Knight's Phantasms.

* Bristleback, Centaur Warrunner, Spirit Breaker, Pudge, Huskar: 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.

* Bristleback is one of the hardest heroes to gank with a Meat Hook and Dismember combo, and attempts to do so sometimes backfire on Pudge.
Additional:
* Pudge is particularly susceptible to Bristleback's Viscous Nasal Goo and Quill Spray due to his naturally low armor & poor agility gain.
* Bristleback, in combination with his strength gain, high health, common itemization for magic resistance and damage reduction from Bristleback makes him a poor target for Pudge.

* Shukuchi will trigger extra damage from Rupture.
* Shukuchi's invisibility is detected by Thirst.
* Time Lapse cannot dispel Rupture, preventing Weaver from escaping ganks.
Additional:
* Rupture is particularly crippling against Weaver, who relies on high movement speed from Shukuchi to fight and escape, and it cannot be dispelled by Time Lapse.
* Thirst detects Weaver through Shukuchi whenever his health is low.
* Blood Rite combined with Rupture forces Weaver to either take damage from the latter, or to get silenced for a long duration.

* Viscous Nasal Goo slows down Dragon Knight and lowers armor, locking him down and making him more vulnerable.

* Quill Spray's constant AoE damage will hit Dark Willow even in Shadow Realm. Its automatic damage will hurt her if she tries to get close and use Bedlam.

* If Thirst activated, Lich doesn't slow Bloodseeker.
* If he sees Chain Frost is targeting him, he can easily isolate himself with Thirst or forces Bloodseeker to build Blade Mail can cause Lich to accidentally kill himself with Chain Frost.
* Even Lich builds Glimmer Cape or Force Staff are suicidal item against Bloodseeker when he is affected by Rupture.

* Blood Rite prevents Anti-Mage from escaping with Blink.
* Blink will trigger the damage from Rupture.
* Both Blood Rite & Rupture are pure damage which can bypass Counterspell.

* Bloodseeker natural attack, run and turn speed outpaces viper's and makes viper easy pickings for Bloodseekers top