Phyrexian Altar + Fiend Hunter + Metamorphosis Fanatic

Phyrexian Altar

Fiend Hunter

Metamorphosis Fanatic

How it works

1. Cast Fiend Hunter by paying its mana cost.
2. When Fiend Hunter enters, its first ability triggers, exiling Metamorphosis Fanatic.
3. Activate Phyrexian Altar by sacrificing Fiend Hunter.
4. When Fiend Hunter dies, its second ability triggers, returning Metamorphosis Fanatic from exile to the battlefield.
5. When Metamorphosis Fanatic enters, it triggers, returning Fiend Hunter from your graveyard to the battlefield.
6. When Fiend Hunter enters, its first ability triggers, exiling Metamorphosis Fanatic.
7. Repeat from step 3.

This elegant loop harnesses a classic exiling-and-returning creature engine to generate an endless supply of resources. By sacrificing Fiend Hunter to Phyrexian Altar, you trigger its departure to instantly bring back Metamorphosis Fanatic from exile. In turn, Metamorphosis Fanatic's entry triggers the return of Fiend Hunter straight from your graveyard back to the battlefield, restarting the cycle and letting you generate infinite colored mana while constantly triggering death and sacrifice events.