Metamorphosis Fanatic, Body Double, and Altar of Dementia

Prerequisites

• Metamorphosis Fanatic in hand
• Body Double in the graveyard
• Altar of Dementia on the battlefield

Steps

1. Cast Metamorphosis Fanatic by paying
2. When Metamorphosis Fanatic enters the battlefield, it triggers, targeting Body Double
3. Holding priority, activate Altar of Dementia by sacrificing Metamorphosis Fanatic, causing target player to mill cards equal to Metamorphosis Fanatic's power
4. Resolve the Metamorphosis Fanatic ability, returning Body Double from your graveyard to the battlefield as a copy of Metamorphosis Fanatic
5. When Body Double enters the battlefield, it triggers, targeting Metamorphosis Fanatic
6. Holding priority, activate Altar of Dementia by sacrificing Body Double, causing target player to mill cards equal to Body Double's power
7. Resolve the Body Double ability, returning Metamorphosis Fanatic from your graveyard to the battlefield
8. Repeat from step 2

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite mill
• Infinite self-mill