Mortuary + Bolas's Citadel + Proper Burial + Carrion Feeder

Mortuary

Bolas's Citadel

Proper Burial

Carrion Feeder

How it works

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

This delightful loop hinges on offsetting Bolas's Citadel's life-payment cost using Proper Burial whenever a creature meets its end. By sacrificing Carrion Feeder to its own activation, Mortuary steps in to instantly recycle the insect back onto the top of your library, exactly where Bolas's Citadel needs it to be cast again. Each iteration of this cycle only costs a single point of life, which Proper Burial happily refunds when Carrion Feeder heads to the graveyard, letting you churn through your entire library, rack up an infinite storm count, and trigger an endless cascade of enters-the-battlefield and death effects.