Mortuary + Bolas's Citadel + Carrion Feeder + Blood Artist

Mortuary

Bolas's Citadel

Carrion Feeder

Blood Artist

How it works

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

This elegant little loop turns your graveyard into a revolving door by anchoring a simple sacrifice outlet to a clever library manipulation enchantment. Whenever you sacrifice Carrion Feeder to its own ability, Mortuary steps in to intercept it from the graveyard and place it right back on top of your library, bypassing conventional death destinations. From there, Bolas's Citadel lets you simply replay the creature directly off the top of your library, substituting the mana cost with a mere 1 life payment that is easily sustained and offset. Meanwhile, Blood Artist watches the constant stream of sacrifices and returns, draining your opponents' life totals and padding your own life buffer with every single cycle.