Agatha's Soul Cauldron, Spike Feeder, and Ageless Entity

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• Spike Feeder in exile
• Ageless Entity on the battlefield
• Ageless Entity has at least one +1/+1 counter on it

Steps

1. Activate Ageless Entity using Spike Feeder's second ability by removing a +1/+1 counter from it, causing you to gain 2 life
2. Ageless Entity triggers, putting two +1/+1 counters on itself
3. Repeat

Results

• Infinite +1/+1 counters on Ageless Entity
• Infinite lifegain
• Infinite lifegain triggers