At the top of the world, where the warpgates of the Old Ones are said to have once stood, lie the Northern Chaos Wastes. The wastes are shifting and insane landscapes where reality and the realms of the daemonic gods of Chaos bleed into one another. The power of Chaos is transformative. Where it broaches on the mundane world it warps things into strange shapes for inscrutable purposes.
Those who find themselves altered by mutation do not immediately fall into the worship of Chaos, despite the proclamations of nobles and priests. To develop a mutation is an incredibly distressing occurrence, not only does the unfortunate mutant find his own flesh in revolt, but his neighbours will view him with horror and sell him out to the authorities – assuming they don’t just kill him themselves...
You can read more about corruption and mutation in my latest designer diary for Winds of Magic.