Mikaeus, the Unhallowed + Viscera Seer + Glen Elendra Archmage

Mikaeus, the Unhallowed

Viscera Seer

Glen Elendra Archmage

How it works

1. Activate Viscera Seer by sacrificing Glen Elendra Archmage.
2. When Glen Elendra Archmage dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
3. Resolve the Viscera Seer ability.
4. Activate Viscera Seer by sacrificing Glen Elendra Archmage.
5. When Glen Elendra Archmage dies, its undying ability triggers, returning it from your graveyard to the battlefield with a +1/+1 counter on it.
6. Resolve the Viscera Seer ability.
7. Repeat.