Mikaeus, the Unhallowed, Ashcloud Phoenix, and Umbral Collar Zealot

Prerequisites

• Mikaeus, the Unhallowed on the battlefield
• Ashcloud Phoenix on the battlefield
• Umbral Collar Zealot on the battlefield

Steps

1. Activate Umbral Collar Zealot by sacrificing Ashcloud Phoenix
2. When Ashcloud Phoenix dies, it triggers, as well as its undying ability if it does not have a +1/+1 counter on it
3. Resolve the first trigger, returning it from your graveyard to the battlefield face-down
4. Resolve the second trigger, doing nothing
5. Activate Umbral Collar Zealot by sacrificing Ashcloud Phoenix
6. When Ashcloud Phoenix dies, it triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it
7. Resolve the Umbral Collar Zealot abilities from steps 1 and 5 Repeat

Results

• Infinite LTB
• Infinite ETB
• Infinite sacrifice triggers
• Infinite death triggers
• Infinite surveil 1