The Three Doctors (Doctor Who) the Third Doctor (Jon Pertwee) for help when Omega drains their civilisation's power. The serial opened the tenth anniversary year of the series, and features the first three Doctors all appearing in the same serial. This makes it the first "Doctor Who" story in which an earlier incarnation of the Doctor returns to the show. A superluminal signal is sent to Earth, carrying with it an energy blob that seems intent on capturing the Doctor. The homeworld of the Time Lords is also under siege, their power being drained through a black hole. Trapped themselves, and desperate to send help,
The Doctor (Doctor Who) of a previous incarnation sustaining mortal injury, though he can regenerate from old age and was once forced to regenerate by the Time Lords. A common side effect the Doctor frequently experiences is a period of instability and partial amnesia following regeneration. Some post-regeneration experiences have been more difficult than others. In particular, the Fifth Doctor began reverting to his previous personalities and required the healing powers of the TARDIS's "Zero Room" to recuperate ("Castrovalva"). The Sixth Doctor experienced extreme paranoia and flew into a murderous rage, nearly killing his companion ("The Twin Dilemma"). The Eighth Doctor experienced amnesia due