Ragaid

In the days of the Old Religion the High Priestesses used to perform a terrible punishment known as Ragaid, the ultimate warning sign from the sorceresses to their enemies which symbolises they have just declared war. The ragaid is a disfigurement of the face caused by extremely powerful magic of the darkest kind, which causes the skin to grow across the victim's face until they suffocate. Morgana performed this magic on a Knight of Camelot to declare war on the whole kingdom (The Kindness of Strangers).