Crackdown Construct, Song of Freyalise, and Endling

Prerequisites

• Crackdown Construct on the battlefield
• Song of Freyalise on the battlefield
• Endling on the battlefield

Steps

1. Activate Endling by tapping it, adding
2. Activate Endling's first ability by paying
3. Crackdown Construct triggers, giving itself +1/+1 until end of turn
4. Resolve the Endling ability, untapping it
5. Repeat

Results

• Infinitely large Crackdown Construct until end of turn