Crackdown Construct, and Mobilized District

Prerequisites

• Crackdown Construct on the battlefield
• Mobilized District on the battlefield
• At least 4 Legendary creatures and/or planeswalkers

Steps

1. Activate District's ability so that it becomes a creature
2. Activate it infinite times again to get infinite Construct triggers
3. Repeat

Results

• Infinitely large Crackdown Construct until end of turn