Phyrexian Altar + Faceless Butcher + Metamorphosis Fanatic

Phyrexian Altar

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 Phyrexian Altar 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. Repeat from step 3.

This clever loop spins an endless cycle of sacrifice and resurrection right on your battlefield. It starts when Faceless Butcher enters to tuck away Metamorphosis Fanatic, which is then fed directly to Phyrexian Altar to generate colored mana and trigger the Butcher's departure. That death releases Metamorphosis Fanatic back to the battlefield, whose own entry trigger immediately pulls Faceless Butcher right out of the graveyard to start the cycle anew.