Malfestation is caused by Soul Edge's curse. It is regarded as a type of cancer, or even an entirely new parasitic organism. However it causes enchanced physical abilities among it's victims, and can cause victims to mutate into more powerful states of being when they experience intense emotion. It can also causes some victims to gain what appears to be some kind of immortality. Malfested animals that act as minions for Soul Edge are known as Watchers. Cervantes' shark, Nightmare's hawk, and Tira's crows are examples of Watchers.