Mikaeus, the Unhallowed, Grinding Station, and Grim Poppet

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Grinding Station on the battlefield
• Grim Poppet 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 without a +1/+1 counter on it due to its replacement effect
3. When Grim Poppet enters, Grinding Station triggers, untapping Grinding Station
4. Resolve the Grinding Station ability from step 1 Repeat

Results

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