Deeproot Pilgrimage, Quicksilver Gargantuan, and Forensic Researcher

Prerequisites

• Deeproot Pilgrimage on the battlefield
• Quicksilver Gargantuan on the battlefield
• Forensic Researcher on the battlefield
• Quicksilver Gargantuan on the battlefield as a copy of Forensic Researcher
• Forensic Researcher and Quicksilver Gargantuan do not have summoning sickness

Steps

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

Results

• Infinite ETB
• Infinite creature tokens