Mortuary + Bolas's Citadel + Panicked Bystander // Cackling Culprit + Accursed Centaur

Mortuary

Bolas's Citadel

Panicked Bystander // Cackling Culprit

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 Panicked Bystander // Cackling Culprit trigger.
4. Resolve the Mortuary trigger, putting Accursed Centaur from your graveyard onto the top of your library.
5. Resolve the Panicked Bystander // Cackling Culprit 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.