Council's seal before he is transmatted to the Zone. The Master encounters the Third Doctor, who dismisses him and accuses him of making the seal himself, before finding the Fifth just as they are surrounded by Cybermen. The Master is knocked out by a Cyberman's gun firing, and the Doctor finds and uses the recall device to return to the Citadel. When the Master awakes, he makes a pact with the Cybermen to lead them to the Tower if they will give him his life but tricks them into falling for the Death Zone's traps. The Cybermen, too, have an ulterior motive, planning to kill the Master when he outlives his usefulness. As the other Doctors and companions converge on the Tower, the Fifth Doctor works with the Council, discovering the recall device given to the Master included a tracking signal to lead the Cybermen to him, and foul play is suspected. The Castellan is found to possess the forbidden Black Scrolls of Rassilon, and he dies while attempting to escape an invasive mind probe. When the Doctor returns to the High Council's chamber to report, he finds Borusa missing, and soon discovers a secret room with Borusa at the controls of the Time Scoop. Borusa reveals he seeks to be the President Eternal of Gallifrey and needed the Doctors to disable the force field over the Tomb in order to gain immortality from Rassilon's Ring and rule forever. Borusa uses his headgear, the Coronet of Rassilon, to compel the Doctor to do his bidding. Meanwhile, the Master meets the First Doctor and Tegan and rids himself of the Cybermen by letting them fall victim to a giant chessboard rigged with a laser trap, before killing the Cyberleader with one of his subordinates' guns. As Borusa expected, the other three Doctors and their companions have made it to the tomb chamber, bypassing the Yeti and Raston Warrior Robot, as well as phantoms of the Doctor's former companions Jamie McCrimmon, Zoe Heriot, Liz Shaw and Mike Yates. They ponder the meaning of writing in the tomb: "to lose is to win and he who wins shall lose". The Master arrives in the Tomb, but the Doctors' companions tie him up, with the Brigadier knocking him out for good measure. The Doctors disable the force field to summon the TARDIS, the Third Doctor using his catchphrase of "I've reversed the polarity of