Mikaeus, the Unhallowed + Altar of Dementia + Wingrattle Scarecrow

Mikaeus, the Unhallowed

Altar of Dementia

Wingrattle Scarecrow

How it works

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