Mikaeus, the Unhallowed + Putrid Goblin + Bloodflow Connoisseur

Mikaeus, the Unhallowed

Putrid Goblin

Bloodflow Connoisseur

How it works

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