Donatello, the Brains, Animation Module, Mutagen Man, Living Ooze, and Crystalline Crawler

Prerequisites

• Donatello, the Brains on the battlefield
• Animation Module on the battlefield
• Mutagen Man, Living Ooze on the battlefield
• Crystalline Crawler on the battlefield

Steps

1. Activate a Mutagen by paying due to Mutagen Man, tapping and sacrificing it, putting a +1/+1 counter on Crystalline Crawler
2. Animation Module triggers
3. Holding priority, activate Crystalline Crawler's first ability by removing a +1/+1 counter from it, adding
4. Resolve the Animation Module trigger, causing you to pay to create a 1/1 Servo artifact creature token and a Mutagen token
5. Repeat

Results

• Infinite ETB
• Infinite creature tokens