Eirdu, Carrier of Dawn // Isilu, Carrier of Twilight, Altar of Dementia, and Cryptborn Horror

Prerequisites

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

Steps

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

Results

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