Mikaeus, the Unhallowed + Carrion Feeder + Thunderblust

Mikaeus, the Unhallowed

Carrion Feeder

Thunderblust

How it works

1. Activate Carrion Feeder by sacrificing Thunderblust.
2. When Thunderblust 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 Thunderblust.
5. When Thunderblust 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.