Carrion Feeder + Faceless Butcher + Metamorphosis Fanatic

Carrion Feeder

Faceless Butcher

Metamorphosis Fanatic

How it works

1. Cast Faceless Butcher by paying its mana cost.
2. When Faceless Butcher enters, its first ability triggers, exiling Metamorphosis Fanatic.
3. Activate Carrion Feeder by sacrificing Faceless Butcher.
4. When Faceless Butcher dies, its second ability triggers, returning Metamorphosis Fanatic from exile to the battlefield.
5. When Metamorphosis Fanatic enters, it triggers, returning Faceless Butcher from your graveyard to the battlefield.
6. When Faceless Butcher enters, its first ability triggers, exiling Metamorphosis Fanatic.
7. Resolve the Carrion Feeder ability.
8. Repeat from step 3.

This clever loop hinges on an infinite recursion between Faceless Butcher and Metamorphosis Fanatic, where each creature constantly resurrects the other through their entering-the-battlefield and leaving-the-battlefield triggers. To make this self-sustaining engine yield an immortal advantage, Carrion Feeder steps in as the sacrifice outlet that breaks the deadlock, letting you repeatedly send Faceless Butcher to the graveyard while growing larger and larger with permanent +1/+1 counters.