Mortuary + Bolas's Citadel + Viscera Seer + Fleshtaker

Mortuary

Bolas's Citadel

Viscera Seer

Fleshtaker

How it works

1. Activate Viscera Seer by sacrificing it.
2. When Viscera Seer dies, Mortuary and Fleshtaker trigger.
3. Resolve the Fleshtaker trigger, causing you to gain 1 life and scry 1.
4. Resolve the Mortuary trigger, putting Viscera Seer from your graveyard onto the top of your library.
5. Resolve the Viscera Seer ability.
6. Cast Viscera Seer from the top of your library by paying 1 life.
7. Repeat.

This clever engine lets you loop your own creatures indefinitely by turning your library into a recursive graveyard-and-back-again conveyor belt. With Bolas's Citadel granting you the power to cast spells straight from the top of your library using life instead of mana, you can continually replay the creature you just sacrificed. Viscera Seer acts as the sacrificial outlet that kicks off the loop, while Mortuary catches that creature on its way to the graveyard and neatly places it right back on top of your library. Meanwhile, Fleshtaker offsets the life you spend on Bolas's Citadel by padding your life total with every sacrifice, ensuring you never run out of juice as you churn through an infinite storm count and endless death triggers.