Deeproot Pilgrimage, Mirrorhall Mimic // Ghastly Mimicry, and Forensic Researcher

Prerequisites

• Deeproot Pilgrimage on the battlefield
• Mirrorhall Mimic // Ghastly Mimicry on the battlefield
• Forensic Researcher on the battlefield
• Mirrorhall Mimic on the battlefield as a copy of Forensic Researcher
• Forensic Researcher and Mirrorhall Mimic do not have summoning sickness

Steps

1. Activate Forensic Researcher by tapping it, targeting Mirrorhall Mimic Deeproot Pilgrimage triggers, creating a 1/1 Merfolk creature token
2. Resolve the Forensic Researcher ability, untapping Mirrorhall Mimic Activate Mirrorhall Mimic by tapping it, targeting Forensic Researcher
3. Deeproot Pilgrimage triggers, creating a 1/1 Merfolk creature token
4. Resolve the Mirrorhall Mimic ability, untapping Forensic Researcher
5. Repeat

Results

• Infinite ETB
• Infinite creature tokens