Mairsil, the Pretender + Carnifex Demon + Cauldron of Souls + Blood Pet + Urabrask the Hidden

Mairsil, the Pretender

Carnifex Demon

Cauldron of Souls

Blood Pet

Urabrask the Hidden

How it works

1. Activate Mairsil using Cauldron of Souls' ability by tapping it, giving itself persist until end of turn.
2. Activate Mairsil using Blood Pet's ability by sacrificing it, adding .
3. When Mairsil dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
4. Activate Mairsil using Carnifex Demon's ability by paying and removing a -1/-1 counter from it, putting a -1/-1 counter on each other creature.
5. Repeat.

By caging these specific pieces, Mairsil, the Pretender becomes a self-contained engine of endless resurrection and decay. Thanks to Urabrask the Hidden granting immediate haste, Mairsil can tap to grant itself persist via Cauldron of Souls, then immediately sacrifice itself to Blood Pet for black mana. When Mairsil dies and returns with a -1/-1 counter from persist, Carnifex Demon's caged ability steps in, allowing you to spend that exact mana to remove the counter, clear the way, and repeat the cycle indefinitely.