Mikaeus, the Unhallowed, Grim Poppet, and Krark-Clan Ironworks

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Grim Poppet on the battlefield
• Krark-Clan Ironworks on the battlefield

Steps

1. Activate Krark-Clan Ironworks by 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. Repeat

Results

• Infinite -1/-1 counters
• Infinite colorless mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers