Mikaeus, the Unhallowed, Grim Poppet, and Grinding Station

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Grim Poppet on the battlefield
• Grinding Station on the battlefield

Steps

1. Activate Grinding Station by tapping it and sacrificing Grim Poppet
2. When Grim Poppet dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. This will be removed by its static ability, which will result in Grim Poppet having two -1/-1 counters instead
4. When Grim Poppet enters, Grinding Station triggers, untapping Grinding Station
5. Resolve the Grinding Station ability from step 1
6. Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite mill
• Infinite self-mill
• Infinite -1/-1 counters