Metamorphosis Fanatic, Phantom Steed, and Yahenni, Undying Partisan

Prerequisites

• Metamorphosis Fanatic in hand
• Phantom Steed in the graveyard
• Yahenni, Undying Partisan on the battlefield
• available

Steps

1. Cast Metamorphosis Fanatic by paying
2. When Metamorphosis Fanatic enters, it triggers, returning Phantom Steed from your graveyard to the battlefield
3. When Phantom Steed enters, it triggers, exiling Metamorphosis Fanatic until Phantom Steed leaves the battlefield
4. Activate Yahenni by sacrificing Phantom Steed
5. When Phantom Steed leaves the battlefield, Metamorphosis Fanatic is returned from exile to the battlefield
6. Repeat from step 2
7. Resolve all Yahenni abilities

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers