Mortuary + Pitiless Plunderer + Vivien, Monsters' Advocate + Yahenni, Undying Partisan

Mortuary

Pitiless Plunderer

Vivien, Monsters' Advocate

Yahenni, Undying Partisan

How it works

1. Activate Yahenni by sacrificing the nontoken creature.
2. When the creature dies, Mortuary and Pitiless Plunderer trigger.
3. Resolve the Mortuary trigger, putting the creature from your graveyard onto the top of your library.
4. Resolve the Pitiless Plunderer trigger, creating a Treasure token.
5. Resolve the Yahenni ability.
6. Activate the Treasure by tapping and sacrificing it, adding one mana of any color.
7. Cast the creature from the top of your library by paying its mana cost
8. Repeat.

This loop transforms a simple sacrifice outlet into a perpetual engine by turning your graveyard into a direct extension of your hand. While Yahenni, Undying Partisan serves as the engine's sacrifice mechanism, Pitiless Plunderer funds the casting costs by spinning off a Treasure token every time a creature bites the dust. Mortuary ensures the sacrificed creature never stays in the graveyard long, immediately placing it back on top of your library where Vivien, Monsters' Advocate steps in to let you recast it directly.