Chronal tumour

Chronal tumours were a symptom caused by the shells of Rassilonian Timeflies. The Time Lords believed that they could bestow an "uncanny knack" for navigating the Time Vortex. (COMIC: The Judas Goatee) During the Last Great Time War, the Master operated on the brain of his TARDIS, causing a chronal tumour to protrude from the side of the console. (COMIC: The One)