Adding in Karl to at least help deal some good damage to the wise snake. He is good with a gun and decently good with a sword, which coupled with super strength can deal decent damage. Plus, he is going to be echoing back this spell, Judgment, which packs a hell of a punch. Any final killing can be left up to someone else, though. He'll just soften ol' Wise Snake up. Also, he can help out with healing everyone else fighting Wise Snake to help keep them going.