The Red Terror, Agatha's Soul Cauldron, and Walking Ballista

Prerequisites

• The Red Terror on the battlefield
• Agatha's Soul Cauldron on the battlefield
• Walking Ballista in exile

Steps

1. Activate The Red Terror using Walking Ballista's second ability by removing a +1/+1 counter from it, dealing 1 damage to any target
2. The Red Terror triggers, putting a +1/+1 counter on it
3. Repeat

Results

• Infinite damage