But the frequency in itself could not cause disturbance between the connection of the skeletons and the Death Knight controlling them. It needed to be accompanied by Frost-based cold attacks. The sound needed to be amplified by blocks of ice. So, he was done creating such a spell and continued to bombard the endless number of undead, jumping all over them as usual.
The effects of the magic spell he created were highly effective, at an expenditure of a minimal amount of energy. As soon as any sharpened block of ice would hit the undead, they would receive physical damage, and that low-frequency sound would spread out from that physical point of impact.
