Mikaeus, the Unhallowed + Trapjaw Kelpie + Carrion Feeder

Mikaeus, the Unhallowed

Trapjaw Kelpie

Carrion Feeder

How it works

1. Activate Carrion Feeder by sacrificing Trapjaw Kelpie.
2. When Trapjaw Kelpie 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 Trapjaw Kelpie.
5. When Trapjaw Kelpie 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.