Agatha's Soul Cauldron, The Thing, Ben Grimm, and Walking Ballista

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• The Thing, Ben Grimm on the battlefield
• Walking Ballista in exile

Steps

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

Results

• Infinite +1/+1 counters on a creature
• Infinite damage