* Enemies that possess high defenses through magic resistance, damage reduction, or high regeneration will make it difficult to whittle their health down to get to Reaper's Scythe's threshold. Such heroes include Bristleback (although only from behind), Spectre, Ursa, and Dragon Knight.

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

* Viper cannot interrupt heroes with powerful channeling abilities: Bane, Enigma, Shadow Shaman, Warlock

* Chaotic Offering's spell immunity piercing stun can stop Black Hole's channeling. Due to this ability's large area of effect, it can be cast at a safe distance from the Black Hole. It also goes through Black King Bar and ignores Linken's Sphere.
* Fatal Bonds and Aghanim's Shard upgraded Shadow Word can be used to make Enigma's Eidolons easier to kill, potentially feeding the enemy team. Also,their constant damage will put Blink Dagger on cooldown, potentially forcing Enigma to prematurely activate Black King Bar.
Additional:
* Chaotic Offering pierces spell immunity and is an area of effect ability, therefore it doesn't matter if Enigma buys Black King Bar or Linken's Sphere, Warlock will always be able to cancel the channeling of Black Hole.
* Enemies often get clumped up around Black Hole to hit your allies, giving you a perfect opportunity to cast Fatal Bonds, Chaotic Offering, and Upheaval on multiple enemies.

* Bristleback's constant harass from Quill Spray will greatly hurt Enigma's laning and kill his Eidolons.
* However, Bristleback has no way of canceling Black Hole at all. And Bristleback is not a hero that goes for disabling items to counter that problem.

* Warlock Golems do plenty of physical and pure damage to bring down Huskar when he is at low health. Warlock is always a hazard for Huskar to initiate by using Life Break, because Chaotic Offering can stun him instantly, even when Black King Bar is activated, and allows Warlock's team to gather their wit and retaliate.
* After using Life Break to jump in, Huskar will not have any means to escape Upheaval. Which since he is an attack-dependent hero, this will nullify his impact in fights.

* 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.
Additional:
* 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.

* Fatal Bonds links the Meepos together, which combined with area of effect damage or Cleave will be devastating.

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

* Channeling heroes will not go well against Warlock, especially those who build Black King Bar as Warlock's ultimate ability stun goes through spell immunity. E.g.: Crystal Maiden, Witch Doctor, Enigma, etc.

* 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.

* Heroes with both illusions and summons, for Io has nothing to deal with multiple enemies at once outside from Spirits's weak area-of-effect: Beastmaster, Broodmother, Chaos Knight, Lycan, Naga Siren, Nature's Prophet, Phantom Lancer, Shadow Shaman, Terrorblade, Visage, Warlock, Wraith King.

* 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.

* Heroes with summons: Lycan, Broodmother, Visage, Nature's Prophet, Warlock.

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

* 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 quickly 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:
* 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.

* Enchant can not control golem Chaotic Offering from Warlock.

* Combo Quill Spray and items Blade Mail can easily trigger from Focus Fire damage.
Additional:
* Using Focus Fire on Bristleback tends to fare badly for Windranger, as he can trigger passive Quill Sprays many times, especially when she attacks him from behind. In addition, Windrun does not protect her from both Viscous Nasal Goo and Quill Spray, rendering her helpless.
* Bristleback's natural tankiness makes it hard for Windranger to effectively burst her down throughout the game.
* Bristleback tends to continuously spam Viscous Nasal Goo to slow down Windranger when she uses Windrun to escape, potentially allowing him to outrun her with his Warpath stacks.
* Bristleback can build Lotus Orb to reflect Shackleshot and Focus Fire back at Windranger.

* 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.

* Warlock has strong counter initiation which reduces Marci's effectiveness throughout the game.
* Fatal Bonds cancels Blink Dagger, which means Marci can move in and out of fights less effectively.
* Chaotic Offering paired with Upheaval provides a ministun, a movement slow and paired with Fatal Bonds has the potential to deal a lot of damage to Marci while she jumps on a target. The ministun also means that Marci will have a harder time casting Rebound. If Warlock does build Aghanim's Scepter and Refresher Orb, the physical damage from Golems will overwhelm Marci, especially when played as a support.

* Arc Warden has relatively lower armor and mobility, which makes him an easy target to apply Quill Spray and Viscous Nasal Goo stacks.
* Arc Warden also does not like to build a Silver Edge as it takes a long time to build up and may slow down the timings for other important items needed in the game like Gleipnir.
* However, do note that in a game where Arc Warden's team has many jumping capabilities or good passives, like a Tidehunter or Spectre, a Silver Edge becomes incredibly valuable on Arc Warden as not only can he run away from the jumps, he effectively gets 2 breaks, and Bristleback may not be the best pick.

* 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 and 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.

* 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.

* Tiny's nonexistent armor in the early game makes him very vulnerable to Quill Spray's large amounts of physical damage.
* Bristleback decreases Tiny's high burst damage against Bristleback.
* Viscous Nasal Goo can slow Tiny to a crawl and allows Bristleback to easily kite him with his high movement speed and Quill Spray's long range, as Tiny has no ability to escape.

* 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

* 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.

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

* 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.

* Illusion and heroes with summons are difficult to kill with Chen's single-target offensive spells: Terrorblade, Phantom Lancer, Chaos Knight, Broodmother, Naga Siren, Lycan, Visage, Beastmaster, Warlock, Wraith King. And even though Chen can convert enemy summons with Holy Persuasion, their much greater numbers will often overwhelm Chen and his creeps.

* Heroes with illusions and summons can be hard for Phantom Assassin to deal with, as she lacks any AoE abilities to deal with them without items: Broodmother, Phantom Lancer, Chaos Knight, Lycan, Naga Siren, Shadow Shaman, Visage, Nature's Prophet, Terrorblade, Warlock, Wraith King.

* Heroes with damage-over-time abilities easily allow Bristleback to turn his back in order to proc Bristleback continuously and to massively reduce to damage dealt to him: Arc Warden, Venomancer, Luna.

Additional:
* Quill Spray and Bristleback harass Luna more efficiently than she does with Lucent Beam.
* Bristleback helps return a lot of damage to Luna’s team if she uses her nukes on him and he has his back to her, and her only way to counter this is by buying Silver Edge.
* Viscous Nasal Goo and Warpath are enough to outrun a speedy Luna.
* Bristleback tends to be a frequent carrier of Crimson Guard and Eternal Shroud, which are good protection from Moon Glaives and Eclipse.
* For the same reasons, Bristleback makes a very powerful ally for Luna when they are in the same team.

* Heroes with channeling spells because Shadow Fiend has nothing to cancel channeling outside of Requiem of Souls: Bane, Enigma, Pudge, Shadow Shaman, Dawnbreaker, Warlock, Crystal Maiden.

Additional:
* Because Shadow Fiend lacks escaping mechanisms, and is dependent on fair positioning for channeling Requiem of Souls, it's easier for Warlock with his long range crowd control abilities to lock Shadow Fiend down for his team.

* Heroes with damage-over-time abilities easily allow Bristleback to turn his back in order to proc Bristleback continuously and to massively reduce to damage dealt to him: Arc Warden, Venomancer, Luna.

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

* Channeling heroes will not go well against Warlock, especially those who build Black King Bar as Warlock's ultimate ability stun goes through spell immunity. E.g.: Crystal Maiden, Witch Doctor, Enigma, etc.

* Warlock often stays back and counter-initiates by dropping his Chaotic Offering on Earthshaker and his allies.

* 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.

* While heroes with strong mobility are able to get close or flee from Upheaval, heroes with no escaping abilities or that lack long disables will perish against Warlock. Once the Warlock Golem lands with its stun, its hardly possible to escape when he casts Upheaval. Notable examples: Huskar, Drow Ranger, Lion, Elder Titan, etc.

* Other heroes who has armor and slow debuffs won't allow Medusa to disengage from combat: Tidehunter, Bristleback, Slardar.

* Heroes with illusions and summons can swarm and overwhelm Bane, who has no area abilities to deal with them outside from Aghanim's Shard upgraded Brain Sap: Broodmother, Chaos Knight, Naga Siren, Nature's Prophet, Phantom Lancer, Terrorblade, Visage, Warlock, Wraith King.

* Chaotic Offering can stop heroes who like to use spell immunity and teleport scrolls to safely farm during the early to mid game, since it stuns and also goes through spell immunity. Notable examples: Juggernaut, Lifestealer.

* While heroes with strong mobility are able to get close or flee from Upheaval, heroes with no escaping abilities or that lack long disables will perish against Warlock. Once the Warlock Golem lands with its stun, its hardly possible to escape when he casts Upheaval. Notable examples: Huskar, Drow Ranger, Lion, Elder Titan, etc.

* Quill Spray quickly destroys Chaos Knight's Phantasms.

* 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.
Additional:
* 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 can still get 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.

* Because Templar Assassin does not have escape potential in lane, any support hero with roaming potential and a Dust of Appearance can be great at shutting her down early game: Earth Spirit, Spirit Breaker, Tusk, Bounty Hunter, Riki, Warlock.

Additional:
* Warlock can cast Upheaval when Templar Assassin uses Meld, preventing her from escaping at the right moment.
* Warlock can also send his Warlock Golem near where she used Meld, preventing escape by Blink Dagger due to the Warlock Golem's Permanent Immolation.
* Warlock's Golem's Permanent Immolation will burn away Refraction with its damage over time.

* Chaotic Offering's vast area-effect can destroy trees and stun Hoodwink.
* Upheaval makes retreating with Scurry difficult.

* 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.

* 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, and Bristleback can simply shrug off all his spells and chase Rubick down with his Quill Spray and the damage bonus from Warpath.
* Rubick does not tend to charge forward in teamfights, stay in the front lines under most circumstances, yet effective casts of Quill Spray and Viscous Nasal Goo requires the opposite as they require multiple casts and close range to add up stacks.
* Rubick does not benefit from Warpath through casting the stolen spell.

* Heroes with summons and illusions as Spirit Breaker has no strong AoE capabilities to deal with them: Chaos Knight, Phantom Lancer, Terrorblade, Naga Siren, Broodmother, Warlock, Visage, Nature's Prophet, Shadow Shaman, Lycan, Wraith King.

* Heroes who can continue dealing damage even while being stunned: Luna, Razor, Axe, Bristleback, Leshrac, Death Prophet, Jakiro.

* While heroes with strong mobility are able to get close or flee from Upheaval, heroes with no escaping abilities or that lack long disables will perish against Warlock. Once the Warlock Golem lands with its stun, its hardly possible to escape when he casts Upheaval. Notable examples: Huskar, Drow Ranger, Lion, Elder Titan, etc.

* 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, Bristleback, Centaur Warrunner, Spirit Breaker, Pudge, Huskar, Wraith King, Doom: 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.