Mortuary + Bolas's Citadel + Blood Artist + Blood Pet

Mortuary

Bolas's Citadel

Blood Artist

Blood Pet

How it works

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

This clever loop turns the sacrifice of Blood Pet into a self-sustaining engine by leveraging Bolas's Citadel to cast creatures directly from the top of your library using life instead of mana. Whenever Blood Pet heads to the graveyard, Mortuary intercepts it to place the creature right back on top of your library, perfectly positioned for the Citadel to recast. Meanwhile, Blood Artist channels this endless cycle of life and death into a lethal drain on your opponents, turning a tiny one-mana sacrifice into an infinite storm of life loss and gain.