Mikaeus, the Unhallowed + Blasting Station + Gravelgill Axeshark

Mikaeus, the Unhallowed

Blasting Station

Gravelgill Axeshark

How it works

1. Activate Blasting Station by tapping it and sacrificing Gravelgill Axeshark.
2. When Gravelgill Axeshark dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. When Gravelgill Axeshark enters, Blasting Station triggers, untapping Blasting Station.
4. Resolve the Blasting Station ability from step 1.
5. Activate Blasting Station by tapping it and sacrificing Gravelgill Axeshark.
6. When Gravelgill Axeshark dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
7. When Gravelgill Axeshark enters, Blasting Station triggers, untapping Blasting Station.
8. Resolve the Blasting Station ability from step 5.
9. Repeat.