Emmara, Soul of the Accord, Agatha's Soul Cauldron, and Forensic Researcher

Prerequisites

• Emmara, Soul of the Accord 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 Emmara
2. Activate Emmara using Forensic Researcher's ability by tapping it
3. Emmara triggers, creating a 1/1 Soldier creature token
4. Resolve the Emmara ability from step 2, untapping another creature
5. Repeat

Results

• Infinite ETB
• Infinite creature tokens