Mortuary + Cauldron Familiar + Bolas's Citadel + Altar of Dementia

Mortuary

Cauldron Familiar

Bolas's Citadel

Altar of Dementia

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 Altar of Dementia 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 Altar of Dementia ability.
6. Repeat.

This loop relies on Bolas's Citadel to cast Cauldron Familiar straight from the top of your library for life instead of mana, bypassing traditional resource constraints. Every time the cat enters the battlefield, its drain ability ticks your opponents down while gaining you life to help offset the Citadel's cost. Altar of Dementia provides a reliable sacrifice outlet to put Cauldron Familiar into the graveyard, which immediately triggers Mortuary to place the creature right back on top of your library, ready to be cast again.