Hmmm, Im not sure if the Prophecy takes MHS parts, but I did see one with the pommel from the Catalyst saber. That could have been done custom though so id check that out before you buy anything. But if it takes MHS pommels you can use any pommel from the MHS range, they all have sound holes in them and are nice and big to increase the resonance of the sound to give it more rumble.
The Prophecy IS COMPATIBLE with all MHS pommels