Mortuary + Gray Merchant of Asphodel + Goblin Bombardment + Bolas's Citadel

Mortuary

Gray Merchant of Asphodel

Goblin Bombardment

Bolas's Citadel

How it works

1. Cast Gray Merchant either from your hand by paying 3 or from the top of your library by paying 5 life.
2. When Gray Merchant enters, it triggers, causing each opponent to lose life equal to your devotion to black and causing you to gain life equal to the life lost this way.
3. Activate Goblin Bombardment by sacrificing Gray Merchant.
4. When Gray Merchant dies, Mortuary triggers, putting Gray Merchant from your graveyard onto the top of your library.
5. Resolve the Goblin Bombardment ability.
6. Repeat.

This lethal loop starts by leveraging Bolas's Citadel, which allows you to cast Gray Merchant of Asphodel directly from the top of your library by paying life instead of its mana cost. Once the Merchant enters the battlefield, its devotion trigger drains your opponents and heals you, providing a comfortable life cushion to offset the Citadel's cost. You then feed the creature to Goblin Bombardment to deal a point of damage and send it to the graveyard. The moment it dies, Mortuary catches it and neatly places it right back onto the top of your library, perfectly positioned for Bolas's Citadel to cast it all over again in an endless cycle of drain, sacrifice, and recycling.