Mikaeus, the Unhallowed, Ashcloud Phoenix, and Altar of Dementia

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Ashcloud Phoenix on the battlefield
• Altar of Dementia on the battlefield

Steps

1. Activate Altar of Dementia by sacrificing Ashcloud Phoenix
2. When Ashcloud Phoenix dies, it triggers, as well as its undying ability if it does not have a +1/+1 counter on it
3. Resolve the first trigger, returning it from your graveyard to the battlefield face-down
4. Resolve the second trigger, doing nothing
5. Activate Altar of Dementia by sacrificing Ashcloud Phoenix
6. When Ashcloud Phoenix dies, it triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
7. Resolve the Altar of Dementia abilities from steps 1 and 5, causing target player to mill cards equal to Ashcloud Phoenix's power for each ability
8. Repeat

Results

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