Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Mighty Mutanimals, and Altar of Dementia

Prerequisites

• Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight on the battlefield
• Mighty Mutanimals on the battlefield
• Altar of Dementia on the battlefield

Steps

1. Activate Altar of Dementia by sacrificing another nontoken creature that doesn't have a -1/-1 counter on it
2. When the creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. When the creature enters, Mighty Mutanimals triggers, putting a +1/+1 counter on the creature
4. Resolve the Altar of Dementia ability
5. Repeat

Results

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