Using Cerebro can be extremely dangerous, and telepaths without well-trained, disciplined minds put themselves at great risk when attempting to use it. This is due to the psychic feedback that users experience when operating Cerebro. As the device greatly enhances natural psychic ability, users who are unprepared for the sheer enormity of this increased psychic input can be quickly and easily overwhelmed, resulting in insanity, coma, permanent brain damage or even death. The one exception has been Magneto, who has been said to have minor or latent telepathic abilities as well as experience amplifying his mental powers with mechanical devices of his own design. Kitty Pryde once upgraded Cerebro so that non-telepaths could use the device. This was during the time that Professor Xavier was with the Shi'ar and Rachel Summers had just left the team. Kitty was able to track Nightcrawler who went missing after a battle with Nimrod.