Grim Poppet, Mirrorhall Mimic // Ghastly Mimicry, and Hapatra, Vizier of Poisons

Prerequisites

• Grim Poppet on the battlefield
• Mirrorhall Mimic // Ghastly Mimicry on the battlefield
• Hapatra, Vizier of Poisons on the battlefield

Steps

1. Activate Grim Poppet by removing a -1/-1 counter from it, putting a -1/-1 counter on Mirrorhall Mimic Hapatra triggers, creating a creature token
2. Activate Mirrorhall Mimic by removing a -1/-1 counter from it, putting a -1/-1 counter on Grim Poppet
3. Hapatra triggers, creating a creature token
4. Repeat

Results

• Infinite ETB
• Infinite creature tokens