Mortuary + Dross Harvester + Bile Urchin + Bolas's Citadel

Mortuary

Dross Harvester

Bile Urchin

Bolas's Citadel

How it works

1. Activate Bile Urchin by sacrificing it.
2. When Bile Urchin dies, Mortuary and Dross Harvester trigger.
3. Resolve the Mortuary trigger, putting Bile Urchin from your graveyard onto the top of your library.
4. Resolve the Dross Harvester trigger, causing you to gain 2 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 transforms Bolas's Citadel into a lethal life-and-death engine by letting you repeatedly cast a single creature from the top of your library for a mere 1 life. Every time you sacrifice Bile Urchin to drain an opponent, Mortuary immediately catches it on its way to the graveyard and places it right back on top of your library for the Citadel to play again. Meanwhile, Dross Harvester steps in to buffer your life total with a 2-life gain for every creature death, more than offsetting the 1-life cost required to cast the Urchin and netting you infinite life loss, storm count, and triggers.