Monster Book says they should be weak to lightning (+50%) however, they are STRONG against it. Is that a bug? Or are they supposed to be weak against a different element?
Probably intended to be weak. Indeed they are strong against it at the moment. Will bring up to see what the deal is.
Castle golems and vultures should both have an elemental weakness now actually. There is a small error in the monster book which will need correcting, though. Have forwarded that over to the devs.