Hapatra, Vizier of Poisons, Skeleton Ship, and Intruder Alarm

Prerequisites

• Hapatra, Vizier of Poisons on the battlefield
• Skeleton Ship on the battlefield
• Intruder Alarm on the battlefield

Steps

1. Activate Skeleton Ship by tapping it, putting a -1/-1 counter on target creature
2. Hapatra triggers, creating a 1/1 Snake creature token
3. The Snake enters the battlefield, triggering Intruder Alarm, untapping all creatures
4. Repeat

Results

• Infinite -1/-1 counters
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite mana creatures you control can produce
• Infinite untap of creatures