Mikaeus, the Unhallowed, Umbral Collar Zealot, and The Reaper, King No More

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Umbral Collar Zealot on the battlefield
• The Reaper, King No More on the battlefield

Steps

1. Activate Umbral Collar Zealot by sacrificing The Reaper
2. When The Reaper dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
3. When The Reaper enters the battlefield, it triggers, putting a -1/-1 counter on it
4. Resolve the Umbral Collar Zealot ability Repeat

Results

• Infinite ETB
• Infinite LTB
• Infinite death triggers
• Infinite sacrifice triggers
• Infinite surveil
• Infinite -1/-1 counters
• Infinite recursion of non-Human creatures you control