Mortuary + Bolas's Citadel + Spore Frog + South Wind Avatar

Mortuary

Bolas's Citadel

Spore Frog

South Wind Avatar

How it works

1. Activate Spore Frog by sacrificing it.
2. When Spore Frog dies, Mortuary and South Wind Avatar's first ability triggers.
3. Resolve the Mortuary trigger, putting Spore Frog 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's second ability triggers, causing each opponent to lose 1 life.
6. Resolve the Spore Frog ability.
7. Cast Spore Frog from the top of your library by paying 1 life.
8. Repeat.