Intruder Alarm, and Elemental Mastery

Prerequisites

• Intruder Alarm on the battlefield
• Elemental Mastery on the battlefield
• Elemental Mastery attached to any creature you control without summoning sickness that has power one or greater

Steps

1. Activate the creature with Elemental Mastery attached by tapping it, creating a number of 1/1 Elemental creature tokens with haste equal to the creatures power
2. The Elementals enter the battlefield, triggering Intruder Alarm that many times
3. Resolve each Intruder Alarm trigger, untapping all creatures
4. Repeat

Results

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