Agatha's Soul Cauldron, Grist, the Hunger Tide, and Warden of the Grove

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• Grist, the Hunger Tide in exile
• Warden of the Grove on the battlefield

Steps

1. Activate a creature using Grist's first loyalty ability by putting a loyalty counter on it, causing you to create a 1/1 Insect creature token and mill a card, and then put a loyalty counter on the creature and repeat the process if the card was an Insect
2. When the Insect enters, Warden of the Grove triggers, putting a +1/+1 counter on the Insect
3. This causes it to gain Grist's abilities due to Agatha's Soul Cauldron
4. Repeat from step 1 using the Insect token instead

Results

• Infinite ETB
• Infinite self-mill
• Infinite creature tokens