Deeproot Pilgrimage, Undercover Operative, and Kiora's Follower

Prerequisites

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

Steps

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

Results

• Infinite ETB
• Infinite creature tokens