Mairsil, the Pretender + Carnifex Demon + Cauldron of Souls + Blood Vassal + Mass Hysteria

Mairsil, the Pretender

Carnifex Demon

Cauldron of Souls

Blood Vassal

Mass Hysteria

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 Vassal'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.

This fascinating loop transforms Mairsil, the Pretender into a self-sustaining engine by eating up abilities from your graveyard. With Mass Hysteria granting haste, Mairsil can immediately tap to borrow Cauldron of Souls' ability to give itself persist, and then sacrifice itself to Blood Vassal for a pair of black mana. When Mairsil returns from the graveyard with a persist-induced -1/-1 counter, you can tap that black mana and use Carnifex Demon's activated ability to strip the counter right back off itself—clearing the way to repeat the entire cycle endlessly.