Deeproot Pilgrimage, Mercurial Pretender, and Kiora's Follower

Prerequisites

• Deeproot Pilgrimage on the battlefield
• Mercurial Pretender on the battlefield
• Kiora's Follower on the battlefield
• Mercurial Pretender on the battlefield as a copy of Kiora's Follower
• Kiora's Follower and Mercurial Pretender do not have summoning sickness

Steps

1. Activate Kiora's Follower by tapping it, targeting Mercurial Pretender
2. Deeproot Pilgrimage triggers, creating a 1/1 Merfolk creature token
3. Resolve the Kiora's Follower ability, untapping Mercurial Pretender
4. Activate Mercurial Pretender by tapping it, targeting Kiora's Follower
5. Deeproot Pilgrimage triggers, creating a 1/1 Merfolk creature token
6. Resolve the Mercurial Pretender ability, untapping Kiora's Follower
7. Repeat

Results

• Infinite ETB
• Infinite creature tokens