so i was wondering, if a vamp is misted, shoudnt' it be able to fly across water or other stuff since it's mist.? Just wondering if we can change it, that way it beats wasting mp to cast fly.

It could be argued that mixing with the mists off the waters, since a vamp mist floats near the service and does not fly through the air, would interfere and make it too taxing for the vampire to continue in mist form over such a long distance.

In essence, creatures in mist form creep along the ground against or just above various surfaces...it doesn't substitute for real flight.