Mikaeus, the Unhallowed, Plague Belcher, and Ashnod's Altar

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Plague Belcher on the battlefield
• Ashnod's Altar on the battlefield

Steps

1. Activate Ashnod's Altar by sacrificing Plague Belcher, adding
2. Plague Belcher dies, triggering its undying ability, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. Plague Belcher enters the battlefield, putting two -1/-1 counters on itself
4. Repeat

Results

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