Mikaeus, the Unhallowed + Ashcloud Phoenix + Carrion Feeder

Mikaeus, the Unhallowed

Ashcloud Phoenix

Carrion Feeder

How it works

1. Activate Carrion Feeder 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 Carrion Feeder 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 Carrion Feeder abilities from steps 1 and 5, putting two +1/+1 counters on it.
8. Repeat.