Card

Bloodletter of Aclazotz

Mana cost {1}{B}{B}{B}

Flying If an opponent would lose life during your turn, they lose twice that much life instead. (Damage causes loss of life.)

Part of 21 known combos, 21 of them two-card. 1 official ruling.

Bracket

B1 Exhibition — Not in the same deck as its two-card combo partners: Peer into the Abyss, Unstoppable Slasher, Blood Tribute, Tree of Perdition, Grievous Wound, Rush of Dread, Shard of the Nightbringer, Betor, Kin to All, Quietus Spike, Revival // Revenge, Fraying Omnipotence, Scourge of the Skyclaves, Shredder, Shadow Master, Virtus the Veiled, Aphelia, Viper Whisperer, Pox Plague, Alpharael, Stonechosen, Dark Leo & Shredder, Scytheclaw, Torgaar, Famine Incarnate, Ebonblade Reaper
B2 Core — Not in the same deck as its two-card combo partners: Peer into the Abyss, Unstoppable Slasher, Blood Tribute, Tree of Perdition, Grievous Wound, Rush of Dread, Shard of the Nightbringer, Betor, Kin to All, Quietus Spike, Revival // Revenge, Fraying Omnipotence, Scourge of the Skyclaves, Shredder, Shadow Master, Virtus the Veiled, Aphelia, Viper Whisperer, Pox Plague, Alpharael, Stonechosen, Dark Leo & Shredder, Scytheclaw, Torgaar, Famine Incarnate, Ebonblade Reaper
B3 Upgraded — Not in the same deck as its early two-card combo partners: Unstoppable Slasher, Blood Tribute, Tree of Perdition, Grievous Wound, Rush of Dread, Betor, Kin to All, Quietus Spike, Revival // Revenge, Fraying Omnipotence, Shredder, Shadow Master, Virtus the Veiled, Aphelia, Viper Whisperer, Pox Plague, Alpharael, Stonechosen, Scytheclaw, Ebonblade Reaper
B4 Optimized — allowed: No restriction beyond the banned list
B5 cEDH — allowed: No restriction beyond the banned list

Two-card combo with Peer into the Abyss, Unstoppable Slasher, Blood Tribute, Tree of Perdition, Grievous Wound, Rush of Dread, Shard of the Nightbringer, Betor, Kin to All, Quietus Spike, Revival // Revenge, Fraying Omnipotence, Scourge of the Skyclaves, Shredder, Shadow Master, Virtus the Veiled, Aphelia, Viper Whisperer, Pox Plague, Alpharael, Stonechosen, Dark Leo & Shredder, Scytheclaw, Torgaar, Famine Incarnate, Ebonblade Reaper (early with Unstoppable Slasher, Blood Tribute, Tree of Perdition, Grievous Wound, Rush of Dread, Betor, Kin to All, Quietus Spike, Revival // Revenge, Fraying Omnipotence, Shredder, Shadow Master, Virtus the Veiled, Aphelia, Viper Whisperer, Pox Plague, Alpharael, Stonechosen, Scytheclaw, Ebonblade Reaper)

Bracket: Lotus Vault analysis, with Commander Spellbook flags

21 known combos, 21 of them two-card.

Peer into the Abyss + Bloodletter of Aclazotz
Produces: Infinite lifeloss for target opponent, Target opponent loses the game
View on Commander Spellbook
Unstoppable Slasher + Bloodletter of Aclazotz
Produces: Target opponent loses the game, Infinite lifeloss for target opponent
View on Commander Spellbook
Bloodletter of Aclazotz + Blood Tribute
Produces: Infinite lifeloss for target opponent, Near-infinite lifegain, Target opponent loses the game
View on Commander Spellbook

2023-11-10 · Wizards of the Coast
Bloodletter of Aclazotz's last ability doesn't change the amount of damage dealt to opponents. For example, if a 1/1 creature with lifelink deals combat damage to an opponent on your turn, they would lose 2 life, but you'd still gain only 1 life.

Rulings: Scryfall · Wizards of the Coast