Mortuary + Bolas's Citadel + Viscera Seer + South Wind Avatar

Mortuary

Bolas's Citadel

Viscera Seer

South Wind Avatar

How it works

1. Activate Viscera Seer by sacrificing it.
2. When Viscera Seer dies, Mortuary and South Wind Avatar trigger.
3. Resolve the Mortuary trigger, putting Viscera Seer from your graveyard onto the top of your library.
4. Resolve the South Wind Avatar trigger, causing you to gain 1 life.
5. South Wind Avatar triggers, causing each opponent to lose 1 life.
6. Resolve the Viscera Seer ability.
7. Cast Viscera Seer from the top of your library by paying 1 life.
8. Repeat.