Phagius

Phagius was a mage in Invidia. He created six magical viruses: the Combustion Virus, the Crystal Virus, the petrification virus, the psionic virus, the phobia virus, and the shadow virus. His intention was to unleash them upon Invidia and use his control of the cures to rule the land. Before this could happen his six children tired of the tyranny of their father and poisoned him. He in turn cursed them and sought to infect them with his creations. As a result each child became a Typhoid Mary for one of the viruses.

Data from the Ravenloft Catalogue

		Ravenloft Monstrous Compendium III
		Ravenloft Monstrous Compendium III - p112