Mortuary + Vein Ripper + Bolas's Citadel + Carrion Feeder

Mortuary

Vein Ripper

Bolas's Citadel

Carrion Feeder

How it works

1. Activate Carrion Feeder by sacrificing it.
2. When Carrion Feeder dies, Mortuary and Vein Ripper trigger.
3. Resolve the Mortuary trigger, putting Carrion Feeder from your graveyard onto the top of your library.
4. Resolve the Vein Ripper trigger, causing you to gain 2 life and target opponent to lose 2 life.
5. Resolve the Carrion Feeder ability.
6. Cast Carrion Feeder from the top of your library by paying 1 life.
7. Repeat.

This ingenious engine uses Bolas's Citadel as its casting engine, allowing you to bypass mana costs entirely and play cards directly from the top of your library by paying life instead. Carrion Feeder acts as the self-sacrificing sacrifice outlet to constantly feed the loop, while Mortuary ensures the sacrificed creature never stays in the graveyard, instantly recycling it right back to the top of your library. Finally, Vein Ripper oversees the entire process with its triggered ability, turning every single death into an unstoppable drain of life that rapidly overwhelms your opponents.