Mikaeus, the Unhallowed + Altar of Dementia + Lesser Masticore

Mikaeus, the Unhallowed

Altar of Dementia

Lesser Masticore

How it works

1. Activate Altar of Dementia by sacrificing Lesser Masticore.
2. When Lesser Masticore 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 Lesser Masticore.
5. When Lesser Masticore 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.