Magic comes with a price, or at the very least a limit. Those that push those limits do so at immense risk. Those that specialise in illusion, transfiguration and magic designed to manipulate the mind, in particular, have to be wary of fracturing their own.Disillusionment is the term for the mental condition caused by overuse of magic where the user has trouble knowing what is real and what is not. Despite sounding as if it only belongs to one school, the condition has been witnessed by users across the schools. The condition is more common with practitioners of Illusion or Transfiguration magic, however. There does appear to be a correlation between people who spend their creating fake images or changing their form and this condition. Outside of Illusionists and Transfigurers, other mages who have fallen to Disillusionment have almost always suffered a traumatic event, which typically will form part of their new perceived reality.
If you require a cautionary tale, look no further than that of Furo Entelles. Once a great Elementalist who, in the name of progress, accidentally burnt his home to the ground and lost his family. Now, he resides in the Magus Baston , permanently believing the world around him is in flames.
HistoricallyDisillusionment is referred to in documents dating back as far as the Age of Discovery, though it is known as Seera Shatad, which in the Olde Tongue would translate to 'The Mind has Broken'. It is presumed, however, that this condition has been around since The Shaping, through the Primordial Age, but there are no remaining documents from that age. Due to the nature of Disillusionment, famous cases of the condition are few and far between. Mages seeking a breakthrough in their field are the ones most at risk, and if they break themselves before they succeed then their names are lost to time. However, there are those that believe Orsa Algrun may have fallen victim to Disillusionment and that was the driving force for her betrayal. That thought is countered by her ability to successfully hide her change in allegiance for months, but it is one theory for an as-yet-unsolved mystery.