That bank is no joke. I was barely able to keep its peasants down during our war and I was in good NW range with 13-14m wpa. Since then, it has had a week to improve WPA (it is mystic...) and it grew in NW also. I'd imagine at this point it is not reasonably possible to cast much magic on it unless that player spent the week jerking it.
Thievery is probably possible, but oping into 2x+ of nw and I assume WTs, I can't see it being terribly effective.