* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.

* Bloodseeker's Thirst, Rupture, and huge AoE silence Blood Rite can fare well against Dazzle.

* Heroes with gap-closing abilities who attempt to use them for escaping Bloodseeker will suffer serious damage from Rupture: Phantom Assassin, Anti-Mage, Faceless Void, Riki, Slark, Spirit Breaker.

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

* Dark Seer can take great advantage of Divided We Stand by putting an Ion Shell on a clone in order to harass them effectively.
* Vacuum can take a single Meepo and disable him for Dark Seer and his teammates to take out.

* Rupture works through Rolling Thunder and Swashbuckle, greatly reducing Pangolier's mobility.
Additional:
* 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, causing 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.

* Certain heroes can mess up with Pangolier's positioning and timing (especially if he intends to use Rolling Thunder during combat): Vengeful Spirit, Keeper of the Light, Huskar, Dark Seer

* Blood Rite can potentially force him to activate Black King Bar 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.

* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.

* 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.

* Ion Shell destroys Refraction's protection stacks in short time.
* Surge ignores the massive slow from Psionic Trap.

* Windrun triggers the damage from Rupture.
Additional:
* Rupture turns Windranger's mobility against her.
* Blood Rite's silence makes Windranger totally useless, since she's extremely reliant on abilities.

* With Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: Phantom Assassin, Windranger, Hoodwink.

* Blood Rite makes Ezalor chose between getting off Illuminate or getting silenced for a while, as Illuminate is a channeled ability.
* Blood Rite's silence can completely take Ezalor out of a teamfight, as he relies on his abilities to be useful.
* Keeper of the Light's only mobility source, his high movement speed (via his high base movement speed and through spirit form), is entirely countered by Rupture.

* Heroes with hastes: Dark Seer, Lycan

* 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.

* The haste provided by Dark Seer's Surge or a {Rune:Haste} renders your slows ineffective.

* 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.

* Living Armor can be destroyed quickly with Ion Shell.

* Heroes with gap-closing abilities who attempt to use them for escaping Bloodseeker will suffer serious damage from Rupture: Phantom Assassin, Anti-Mage, Faceless Void, Riki, Slark, Spirit Breaker.

* With Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: Phantom Assassin, Windranger, Hoodwink.

* 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 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.

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

* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: Phantom Lancer, Chaos Knight, Naga Siren, Terrorblade.

* Rupture and Blood Rite locks down Timbersaw, preventing him from escaping with Timber Chain. However, Timbersaw may reflect a good deal of damage with Blade Mail.

* Dark Seer's Vacuum and Ion Shell allows him to clear a wave of Terrorblade's illusions.
* Because Terrorblade often builds items that require Ultimate Orb like Manta Style and Eye of Skadi, Dark Seer can create a very strong illusion of Terrorblade with Wall of Replica and Normal Punch from Aghanim's Scepter.
* If Dark Seer can use Vacuum to help teammates land their AoE abilities, Terrorblade will be quickly killed before he even gets a chance to use Sunder.
Additional:
* Dark Seer's Vacuum and Ion Shell allows him to clear a wave of Terrorblade's illusions.
* Because Terrorblade often builds items that require Ultimate Orb like Manta Style and Eye of Skadi, Dark Seer can create a very strong illusion of Terrorblade with Wall of Replica and Normal Punch from Aghanim's Scepter.
* If Dark Seer can use Vacuum to help teammates land their AoE abilities, Terrorblade will be quickly killed before he even gets a chance to use Sunder.

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

* 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.

* Bloodseeker is one of the hardest counters to Slark.Thirst prevents Slark from healing in lane with Shadow Dance and may set him up for a kill while in the jungle,or retreating.
* Rupture will deal damage during Pounce.
* Dark Pact cannot dispel Rupture, preventing Slark from escaping ganks.
Additional:
* Thirst stops Shadow Dance's passive health regeneration if Slark's current health is below the Thirst's visibility threshold.
* Rupture effectively diminishes Slark's mobility in battle, leaving him susceptible to AoE stuns or forcing to teleport out of the fight.

* Heroes with AoE abilities will hit Slark in Shadow Dance: Lina, Jakiro, Underlord, Leshrac, Dark Seer, Earthshaker, Timbersaw, Crystal Maiden.

* 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.

* Primal Beast's abilities require movement to deal damage, making Rupture potentially deadly and debilitating. Furthermore, its initial damage based on the target's current health is devastating to a full-health Primal Beast with his high strength gain and thus high HP.
* Due to his reliance on spells, Primal Beast is vulnerable to Blood Rite's powerful silence without items to counter it.

* Phoenix expends health to use its abilities, making it a good target for Thirst.
* Rupture deals heavy damage against Icarus Dive.
Additional:
* 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 through Thirst, making it a very tempting ganking target.

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

* Rupture ruins her only movement ability, Rebound. Combined with its high movement speed and her being unable to interrupt it once its cast, using it under the effects of Rupture will surely deal incredibly immutable damage, if not kill her.
* As a Strength hero, Marci naturally has high HP. Rupture's initial damage uses her high HP as a catalyst to deal damage depending on her current health, dealing a good amount of damage if she's full HP or forcing her to stop if she's low.
* With Aghanim's Shard, Bloodrage will now deal pure damage and lifesteal based on the opponent's max health. Her high HP as a Strength hero ensures that Bloodseeker will always deal significant attack damage and sustain himself a lot whenever he attacks Marci.
* If Marci doesn't build Black King Bar, Bloodseeker's Blood Rite will prevent her from using all of her spells which she relies quite heavily on. Her only dispel is tied to Sidekick with level 25 left talent.

* 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.

* Venomancer is a low health hero and low range hero who is easy to harass with Ion Shell on a creep in the early game.
* Venomancer depends entirely on all his slows to keep distance or chase, but since Surge ignores slows, it is nearly impossible for Venomancer to hunt or run away from Dark Seer or his surged teammates.

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

* Ion Shell zones out Broodmother in the laning phase, and can kill her spiderlings if used on one Spiderling in a group.
* Vacuum can pull Broodmother out of the treeline.
Additional:
* Ion Shell is a very powerful weapon against Broodmother's Spiderlings and makes her laning much harder.

* Skeleton Walk is not enough to outrun Bloodseeker, and is detected by Thirst.
* Because of his low health and high damage output, Clinkz will get obliterated by Blade Mail
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.

* Huskar is often at low health, providing large Thirst bonuses.
* Life Break triggers Rupture's damage.
Additional:
* 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

* 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.

* Dark Seer's Vacuum and Ion Shell can clear a wave of Chen's Creeps effectively.
* Surge applies haste movement and negates the slow from Penitence, allowing Dark Seer to easily escape from Chen and his creeps.
* Dark Seer's full combo from Dark Seer's Vacuum, Wall of Replica and Normal Punch from Aghanim's Scepter can often kill Chen or any of his allies before he can save them with Hand of God.
Additional:
* Dark Seer's Vacuum and Ion Shell can clear a wave of Chen's Creeps effectively.
* Surge applies haste movement and negates the slow from Penitence, allowing Dark Seer to easily escape from Chen and his creeps.
* Dark Seer's full combo from Dark Seer's Vacuum, Wall of Replica and Normal Punch from Aghanim's Scepter can often kill Chen or any of his allies before he can save them with Hand of God.

* Heroes with haste can negate Enchant's slow: Weaver, Dark Seer, Lycan, Centaur Warrunner.

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

* With Normal Punch from Aghanim's Scepter, Dark Seer can gain an advantage against heroes who rely on evasion as Normal Punch has true strike: Phantom Assassin, Windranger, Hoodwink.

* Heroes who do not have nor rely on passive abilities make Nethertoxin much less effective: Clinkz, Pugna, Nature's Prophet, Dark Seer, Lycan, Tusk

* Heroes with gap-closing abilities who attempt to use them for escaping Bloodseeker will suffer serious damage from Rupture: Phantom Assassin, Anti-Mage, Faceless Void, Riki, Slark, Spirit Breaker.

* 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:
* 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, as it provides True Sight.

* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.

Additional:
* Surge allows for Dark Seer and his allies to escape from Upheaval due to it ignoring any slow.

* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.

* Heroes with escape abilities : Anti-Mage Dark Seer Slark Storm Spirit Windranger Weaver can kite Lifestealer due to him having no lockdown

* 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.

* 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 and mutes 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.

* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: Phantom Lancer, Chaos Knight, Naga Siren, Terrorblade.

Additional:
* Ion Shell helps taking down illusions quickly, making it easy to identify the real Phantom Lancer.
* Surge allows Dark Seer and his teammates to run away from Phantom Lancer, who relies on his Phantom Rush to chase enemies.

* 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.

* 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.

* Dark Seer can pull together Spectre's illusions with Vacuum, and Wall of Replica creates an illusion of Spectre that deals massive damage.

* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.

* Bloodseeker's Rupture forces Slardar to stay still during fights, preventing Slardar from using Guardian sprint to move in and out of fights. This takes away the ability to initiate and re-initiate with Slithereen Crush's low cooldown. Due to the increased move speed from Guardian Sprint, Slardar can lose health at about 160% the rate of normal heroes while under Rupture. Bloodseeker's Thirst also gives him enough move speed so that he's one of the few heroes who can outrun or catch up to a Slardar during Guardian Sprint.

* Blood Rite prevents Queen of Pain from escaping with Blink.
* Blink will trigger the extra damage from Rupture.
Additional:
* 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 successfully blink-walks.

* Shukuchi will trigger extra damage from Rupture.
* Shukuchi's invisibility is detected by Thirst.
* Time Lapse cannot dispel Rupture, preventing Weaver from escaping ganks. However, smart Weaver will buy Linken's Sphere to counter this problem for him.
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.

* Dark Seer can increase the movement speed of allies with Surge, breaking Static Link.

* Heroes that rely on summons will suffer against Ion Shell, which kills them very quickly: Beastmaster, Broodmother, Enigma, Nature's Prophet, Visage, Warlock, Wraith King.

* Heroes who are strong against mobile heroes: Disruptor, Bloodseeker, Kunkka, Keeper of the Light.

* 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.

* Sniper's lack of mobility and escape mechanisms makes him one of the easier heroes for Bloodseeker to gank.

* 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.

* Heroes that rely on illusions typically spawn very strong illusions inside Dark Seer Wall of Replica that he can use against them or their team: Phantom Lancer, Chaos Knight, Naga Siren, Terrorblade.