[Name] Vile Diseases [Source] Book of Vile Darkness [Symptoms] 
The book mentions seventeen diseases of varying lethality caused by evil magic or exposure to focal points of incredible evil. The most notorious ones are Faceless Hate (causes the victim's face to vanish, and drives him to a violent, insane rage), Life Blindness (the victim is unable to see, hear, or otherwise perceive any other living things, and is often driven mad from isolation and loneliness), and Vile Rigidity (the victim becomes stronger and tougher, but eventually, his skin hardens, until he can't move and suffocates).