[Shostak]

On further reflection, I think that, since this is a spell that will kill its subject, the main spell effect here is Destroy Body and that it requires a damage modifier that will deal enough damage to kill. The crawling critter part is really just cool color. If not enough damage is done, then not enough critters crawl far enough away for the victim's body to be dispersed. I would probably not even charge for the transformation effect, since to do so would just encourage players to leave the cool bits out in favor of the lowest cost spell possible.