Mikaeus, the Unhallowed + Bloodied Ghost + Viscera Seer

Mikaeus, the Unhallowed

Bloodied Ghost

Viscera Seer

How it works

1. Activate Viscera Seer by sacrifiicing Bloodied Ghost.
2. When Bloodied Ghost dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it. When it enters, Bloodied Ghost will put a -1/-1 counter on itself, removing the +1/+1 counter.
3. Resolve the Viscera Seer ability.
4. Repeat.