Mortuary + Bolas's Citadel + Goblin Firestarter + Popular Egotist

Mortuary

Bolas's Citadel

Goblin Firestarter

Popular Egotist

How it works

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

This loop sets up a self-sustaining engine right off the top of your library. Bolas's Citadel allows you to play Goblin Firestarter directly from the library while substituting its mana cost with a simple payment of 1 life. Once sacrificed to its own ability, Mortuary immediately catches Goblin Firestarter on its way to the graveyard and cycles it right back to the top of the library. Meanwhile, Popular Egotist weaponizes the entire process, turning every single sacrifice loop into a guaranteed drain of your opponent's life total while padding your own life buffer to safely keep paying the Citadel's cost.