Mortuary + Bolas's Citadel + Spore Frog + Venerated Stormsinger

Mortuary

Bolas's Citadel

Spore Frog

Venerated Stormsinger

How it works

1. Activate Spore Frog by sacrificing it.
2. When Spore Frog dies, Mortuary and Venerated Stormsinger trigger.
3. Resolve the Mortuary trigger, putting Spore Frog from your graveyard onto the top of your library.
4. Resolve the Venerated Stormsinger trigger, causing you to gain 1 life and each opponent to lose 1 life.
5. Resolve the Spore Frog ability.
6. Cast Spore Frog from the top of your library by paying 1 life.
7. Repeat.

This clever loop uses Bolas's Citadel to cast Spore Frog straight from the top of your library for a mere 1 life instead of its mana cost, keeping the engine fueled by leveraging your life total. Whenever Spore Frog dies, Mortuary ensures the little amphibian goes right back to the top of your library instead of staying in the graveyard, while Venerated Stormsinger rewards every single death and entry with life drain. Because Venerated Stormsinger's trigger nets you 1 life every iteration, it completely offsets the 1 life you pay to cast Spore Frog, allowing you to repeat this cycle endlessly to drain the table while fogging combat indefinitely.