Skeleton Ship, Intruder Alarm, Geralf's Mindcrusher, and Altar of Dementia

Prerequisites

• Skeleton Ship on the battlefield
• Intruder Alarm on the battlefield
• Geralf's Mindcrusher on the battlefield
• Altar of Dementia on the battlefield
• Skeleton Ship does not have summoning sickness
• Geralf's Mindcrusher does not have a +1/+1 counter on it

Steps

1. Activate Altar of Dementia by sacrificing Geralf's Mindcrusher
2. Geralf's Mindcrusher dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. Geralf's Mindcrusher enters the battlefield, triggering itself and Intruder Alarm
4. Resolve the Geralf's Mindcrusher trigger, causing target player to mill five cards
5. Resolve the Intruder Alarm trigger, untapping all creatures
6. Resolve the Altar of Dementia ability from step 1, causing target player to mill cards equal to Geralf's Mindcrusher's power
7. Activate Skeleton Ship by tapping it, putting a -1/-1 counter on Geralf's Mindcrusher
8. Repeat

Results

• Infinite death triggers
• Infinite ETB
• Infinite lifeloss
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill
• Infinite untap of all creatures