Mortuary + Bolas's Citadel + Bontu's Monument + Yahenni, Undying Partisan

Mortuary

Bolas's Citadel

Bontu's Monument

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing a creature with mana value 1 or less.
2. When the creature dies, Mortuary triggers, putting the creature from your graveyard onto the top of your library.
3. Resolve the Yahenni ability.
4. Cast the creature from the top of your library by paying 1 life.
5. Bontu's Monument triggers, causing you to gain 1 life and each opponent to lose 1 life.
6. Repeat.

This loop turns a modest sacrifice into an unstoppable engine by leveraging Bolas's Citadel to cast spells directly from the top of your library while bypassing traditional mana costs with your life total. Whenever you sacrifice a cheap creature to Yahenni, Undying Partisan, Mortuary immediately catches it on its way to the graveyard and stacks it right back on top of your library for the Citadel to play again. Meanwhile, Bontu's Monument eases the life-payment burden by gaining you life on every single recast while slowly draining your opponents out of the game.