Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Solemnity, and Altar of Dementia

Prerequisites

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

Steps

1. Activate Altar of Dementia by sacrificing another nontoken creature without a -1/-1 counter on it
2. When the creature dies, its persist ability triggers, returning it from your graveyard to the battlefield without a -1/-1 counter on it due to Solemnity
3. Resolve the Altar of Dementia ability
4. Repeat

Results

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