Shyish
Shyish was originally the wind of magic related to all things to do with death. Despite what you may think, technically in the Old World system Necromancy counts as Dark Magic (which is made of all the Winds mixed together), not Shyish magic. In the Age of Sigmar it has become the realm of Nagash. Shyish serves as the afterlife for the mortal realms: underworlds containing the souls of the dead are formed based on the beliefs of various cultures.