Cacophodon, Guilty Conscience, and Viridian Longbow

Prerequisites

• Cacophodon on the battlefield
• Guilty Conscience on the battlefield
• Viridian Longbow on the battlefield

Steps

1. Activate Cacophodon by tapping it, dealing damage to any target
2. Guilty Conscience triggers, dealing damage to Cacophodon
3. Cacophodon triggers, untapping itself
4. Repeat

Results

• Infinite damage