Mikaeus, the Unhallowed, Otherworldly Escort, and Altar of Dementia

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Otherworldly Escort on the battlefield
• Altar of Dementia on the battlefield

Steps

1. Activate Altar of Dementia by sacrificing Otherworldly Escort
2. When Otherworldly Escort dies, it triggers, returning itself from your graveyard to the battlefield as a Spirit Detective
3. Resolve the Altar of Dementia ability
4. Activate Altar of Dementia by sacrificing Otherworldly Escort
5. When Otherworldly Escort dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
6. Resolve the Altar of Dementia ability
7. Repeat

Results

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