Soulbleed

On its way to the realms of Lord Thoth, fractional amounts of death energy are lost in transit. This leaked energy, known as soulbleed, collects on the infernal plane of the Underworld where it coalesces into undead beings. King Ugrach is said to have discovered a way to mould soulbleed into beings of his own liking, an ability the Magister Dominar covets highly.