User blog comment:Onic14/Nature of the Slayers/@comment-24934658-20140728223848/@comment-77.253.86.140-20140729112214

Or God Slaying Magic, was created to fight/kill other Slayers. Normal magic in most cases can't do anything to DS, and as we know DS came to world by dragons. Humans that learnt that magic was eventually fired of their jobs with dissaperance of dragons. So some of them would try to seize power over humans, thus almost like gods that can't be killed with normal magic, someone came up with idea of slayer magic, that other slayers can't eat. Maybe, maybe not, hopefully Mashima will explain GS magic.