Mortuary + Bile Urchin + Bolas's Citadel + Susurian Voidborn

Mortuary

Bile Urchin

Bolas's Citadel

Susurian Voidborn

How it works

1. Activate Bile Urchin by sacrificing it.
2. When Bile Urchin dies, Mortuary and Susurian Voidborn trigger.
3. Resolve the Mortuary trigger, putting Bile Urchin from your graveyard onto the top of your library.
4. Resolve the Susurian Voidborn trigger, causing you to gain 1 life and target opponent to lose 1 life.
5. Resolve the Bile Urchin ability.
6. Cast Bile Urchin from the top of your library by paying 1 life.
7. Repeat.

This clever loop turns the graveyard into a reliable conveyor belt, using Bolas's Citadel to cast spells directly from the top of your library by paying life instead of mana. When you sacrifice Bile Urchin to drain your opponent, Mortuary ensures the mischievous little creature immediately returns to the top of your library to be recast. Meanwhile, Susurian Voidborn watches your permanents die to continually siphon life away from your opponent and pad your own life total, easily offsetting the life costs required to keep the Citadel running.