Mortuary + Vindictive Vampire + Bolas's Citadel + Carrion Feeder

Mortuary

Vindictive Vampire

Bolas's Citadel

Carrion Feeder

How it works

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

This lethal loop turns your graveyard into a revolving door by letting you feed Carrion Feeder to its own sacrifice ability over and over. Thanks to Mortuary, the sacrificed creature never stays in the graveyard, instead heading straight back to the top of your library where Bolas's Citadel allows you to recast it instantly by paying a meager 1 life. Meanwhile, Vindictive Vampire watches the endless procession of dying creatures to drain your opponents of their life totals and keep your own life buffer comfortably topped off to fuel the Citadel.