Mikaeus, the Unhallowed + Carrion Feeder + Persistent Constrictor

Mikaeus, the Unhallowed

Carrion Feeder

Persistent Constrictor

How it works

1. Activate Carrion Feeder by sacrificing Persistent Constrictor.
2. When Persistent Constrictor dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Resolve the Carrion Feeder ability.
4. Activate Carrion Feeder by sacrificing Persistent Constrictor.
5. When Persistent Constrictor dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. Resolve the Carrion Feeder ability.
7. Repeat.