Mortuary + Bolas's Citadel + Carrion Feeder + Fear of Lost Teeth

Mortuary

Bolas's Citadel

Carrion Feeder

Fear of Lost Teeth

How it works

1. Activate Carrion Feeder by sacrificing Fear of Lost Teeth.
2. When Fear of Lost Teeth dies, it and Mortuary triggers.
3. Resolve the Mortuary trigger, putting Fear of Lost Teeth from your graveyard onto the top of your library.
4. Resolve the Fear of Lost Teeth trigger, causing you to gain 1 life and dealing 1 damage to any target.
5. Resolve the Carrion Feeder ability.
6. Cast Fear of Lost Teeth from the top of your library by paying 1 life due to Bolas's Citadel.
7. Repeat.

This elegant little loop turns Bolas's Citadel from a powerful card-advantage engine into a lethal finisher by letting you cast the same permanent over and over directly from the top of your library. Carrion Feeder acts as the sacrifice outlet that puts your engine into motion, while Mortuary neatly catches the creature as it hits the graveyard and immediately recycles it back to the top of your library. Meanwhile, Fear of Lost Teeth serves as the perfect recursive fuel for the loop; every time it is sacrificed, its own death trigger gains you the life needed to offset the mana value payment demanded by Bolas's Citadel, while simultaneously burning down your opponents with endless damage.