I would say this card needs a Potion cost, and must act as an intermediate station on the upgrading path to Province.
Give it 3P. So let it upgrade 3++->3P, and 3P->$8 should at least seems like it might have something to do as only Potion-cost card.
$3P->$8 seems like a great jump, but counting P as $2 it's "only" a $3 upgrade, like Expand. Taking into account that there are not that many targets with P, that is not that bad maybe.