Mikaeus, the Unhallowed, Defiant Greatmaw, and Altar of Dementia

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Defiant Greatmaw on the battlefield
• Altar of Dementia on the battlefield
• Defiant Greatmaw does not have a +1/+1 counter on it

Steps

1. Activate Altar of Dementia by sacrificing Defiant Greatmaw
2. When Defiant Greatmaw dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. When Defiant Greatmaw enters the battlefield, its first ability triggers, putting two -1/-1 counters on it
4. Defiant Greatmaw's second ability triggers, removing a -1/-1 counter from another creature you control
5. Resolve the Altar of Dementia ability from step 1, causing target player to mill cards equal to Defiant Greatmaw's power
6. Repeat

Results

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