Hmm...I guess I sort of imagine it as a bit bigger than the moon, with this being really the only spot with any real vegetation or civilization....but that's just me. So knocking one-fourth of it off will screw with its orbit around its star, unless the bar has the power to fix that as well...
Besides, I don't want to interrupt both of my characters' interactions just because the place is being demolished...it is a bit powergamey guys, you might have to do away with how much damage this thing is going to create. Can't you just zap the vampire, or something?