Agatha's Soul Cauldron, Dr. Beverly Crusher, and Deathbringer Thoctar

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• Dr
• Beverly Crusher on the battlefield
• Deathbringer Thoctar in exile

Steps

1. Activate Dr
2. Beverly Crusher by using Deathbringer Thoctar's ability by removing a +1/+1 counter from it, dealing 1 damage to any target and causing you to gain 1 life due to its lifelink
3. Dr
4. Beverly Crusher triggers, putting two +1/+1 counters on it
5. Repeat

Results

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