Mortuary + Bolas's Citadel + Moonlit Wake + Accursed Centaur

Mortuary

Bolas's Citadel

Moonlit Wake

Accursed Centaur

How it works

1. Cast Accursed Centaur by paying its mana cost.
2. Activate Accursed Centaur by sacrificing it.
3. When Accursed Centaur dies, Mortuary and Moonlit Wake trigger.
4. Resolve the Mortuary trigger, putting Accursed Centaur from your graveyard onto the top of your library.
5. Resolve the Moonlit Wake trigger, causing you to gain at least 1 life.
6. Cast Accursed Centaur from the top of your library by paying 1 life.
7. Repeat from step 2.