Umbrinius

Umbrinius, also known as the Dharland Plague, the Demon or Demonic Plague, or simply as the Black Sickness, is an ailment that causes the sufferer's skin to turn a dark ash-grey. It is the most common side-effect within creatures, especially humans, who live on the island of Dharland for long periods of time. Umbrinius has no cure and seems to be permanent once its effects show up.