Blasting Station | Hardened Academic (and one other card)

Persist Creature

Cards

Activate
Blasting Station by tapping it and sacrificing the creature with persist.
When that creature dies, its persist ability triggers, returning it from your graveyard to the battlefield with a -1/-1 counter on it.
Hardened Academic and
Blasting Station trigger.
Resolve the
Blasting Station trigger, untapping it.
Resolve the
Hardened Academic trigger, putting a +1/+1 counter on the Persist Creature.
Remove a +1/+1 counter and a -1/-1 counter from that creature as a state-based action.
Resolve the
Blasting Station ability from step 1.
Repeat.

This combo has been estimated to be Exhibition (Bracket 1+).