When a magus loses control over their magic, he suffers Wizard's Twilight. All things are affected in some way by their interaction with the forces of magic, an effect called warping. Practitioners from other magical traditions react differently to warping, but Wizard's Twilight is the reaction of magi trained in the Hermetic tradition. While the effects of twilight vary greatly, if a magus is able to comprehend the twilight episode the effects can be advantageous. Conversely, if they fail to understand the episode the effects are bad.
When a magus with a lot of warping suffers final twilight the effects can be more dramatic. Sometimes the magus is consumed by their own magic, while Bjornaer magi often permanantly take the form of their heartbeast. A magus who specializes in Terram magic might permanantly become a statue.