Mikaeus, the Unhallowed, Carnifex Demon, and Ashnod's Altar

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Carnifex Demon on the battlefield
• Ashnod's Altar on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Carnifex Demon, adding
2. Carnifex Demon dies, triggering its undying ability, returning it from your graveyard to the battlefield with a -1/-1 counter on it
3. Repeat

Results

• Infinite colorless mana
• Infinite death triggers
• Infinite ETB
• Infinite LTB
• Infinite sacrifice triggers