Agatha's Soul Cauldron, Deeproot Pilgrimage, and Clever Conjurer

Prerequisites

• Agatha's Soul Cauldron on the battlefield
• Deeproot Pilgrimage on the battlefield
• Clever Conjurer in exile

Steps

1. Activate the nontoken Merfolk using Clever Conjurer's ability by tapping it
2. Deeproot Pilgrimage triggers, creating a 1/1 Merfolk creature token
3. Resolve the Merfolk's ability, untapping the other creature
4. Activate the other creature using Clever Conjurer's ability by tapping it, untapping the nontoken Merfolk
5. Repeat

Results

• Infinite ETB
• Infinite creature tokens