Mortuary + Cauldron Familiar + Bolas's Citadel + Goblin Bombardment

Mortuary

Cauldron Familiar

Bolas's Citadel

Goblin Bombardment

How it works

1. Cast Cauldron Familiar either from your hand or from the top of your library by paying or 1 life respectively.
2. When Cauldron Familiar enters, it triggers, causing each opponent to lose 1 life and you to gain 1 life.
3. Activate Goblin Bombardment by sacrificing Cauldron Familiar.
4. When Cauldron Familiar dies, Mortuary triggers, putting Cauldron Familiar from your graveyard onto the top of your library.
5. Resolve the Goblin Bombardment ability.
6. Repeat.

This intricate loop transforms a humble cat into an engine of absolute doom by turning graveyard movement back into library access. With Bolas's Citadel providing the top-deck casting permission, you can continuously cast Cauldron Familiar for a mere 1 life instead of its mana cost, triggering its life-draining effect immediately upon entry. Goblin Bombardment then provides the sacrifice outlet to send the cat away, which instantly triggers Mortuary to place Cauldron Familiar right back on top of your library for the Citadel to play again.