Intruder Alarm, Stonybrook Schoolmaster, and Opposition

Prerequisites

• Intruder Alarm on the battlefield
• Stonybrook Schoolmaster on the battlefield
• Opposition on the battlefield

Steps

1. Activate Opposition by tapping Stonybrook Schoolmaster, targeting Stonybrook Schoolmaster
2. Stonybrook Schoolmaster triggers, creating a 1/1 Merfolk Wizard creature token
3. The Merfolk Wizard enters the battlefield, triggering Intruder Alarm, untapping all creatures
4. Resolve the Opposition ability, tapping Stonybrook Schoolmaster
5. Stonybrook Schoolmaster triggers, creating a 1/1 Merfolk Wizard creature token
6. The Merfolk Wizard enters the battlefield, triggering Intruder Alarm, untapping all creatures
7. Repeat

Results

• Infinite creature tokens
• Infinite ETB
• Infinite mana creatures you control can produce
• Infinite untap of all creatures