Neerdiv, Devious Diver, Agatha's Soul Cauldron, and Forensic Researcher

Prerequisites

• Neerdiv, Devious Diver on the battlefield
• Agatha's Soul Cauldron on the battlefield
• Forensic Researcher in exile

Steps

1. Activate a creature using Forensic Researcher's ability by tapping it, untapping Neerdiv
2. Activate Neerdiv using Forensic Researcher's ability by tapping it
3. Neerdiv triggers, causing a player to mill cards equal to its power
4. Resolve the Neerdiv ability from step 2, untapping another creature
5. Repeat

Results

• Infinite mill
• Infinite self-mill