I doubt Xykon has had the time to learn another epic spell in the month or two since it was cast. He had to drop stuff off at his secret hidey hole, teleport to the prophesized location, and since then he's been fighting near epic monsters daily. Epic spell research takes weeks of concentrated effort and besides Superb Dispelling and Cloister, he probably knows one more epic spell, probably a blasting one.

Besides, Xykon is probably only going to kill Belkar, unless the two die to the Snarl at the same time. Or at least the same comic. Any other character deaths (besides villains) are unlikely.