Skeleton Ship, Intruder Alarm, Geralf's Mindcrusher, and Carrion Feeder

Prerequisites

• Skeleton Ship on the battlefield
• Intruder Alarm on the battlefield
• Geralf's Mindcrusher on the battlefield
• Carrion Feeder 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 Carrion Feeder 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 Carrion Feeder ability from step 1, putting a +1/+1 counter on it
7. Activate Skeleton Ship by tapping it, putting a -1/-1 counter on Geralf's Mindcrusher
8. Repeat

Results

• Infinite +1/+1 counters on Carrion Feeder
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite mill
• Infinite sacrifice triggers
• Infinite self-mill
• Infinite untap of all creatures