Cult of the Heretic The Cult of the Heretic were a religious group dedicated to worshipping the renegade Time Lord known as the Heretic . Their goal was to regenerate the universe to become its new rulers . Although they worshipped a Time Lord , none of the cult members were Gallifreyan . The cult was started by the Heretic , who used the cult to construct an anomaly cage . The Doctor stopped the cult from using the Heretic ' s biodata to regenerate the universe and the Heretic was taken by the Time Lord s . Needing another Time Lord to activate the restart the universe , the cult made a deal with , who had come to offer them his DNA in return for a position of power in their recreated universe . They manipulated him into coming into contact with his , claiming that they wanted him to kill his past self to prove his dedication to their cause . After the Master had crippled his past self , the Cult betrayed the Master by knocking out the future Master and transferring the past Master into his future self , leaving the older Master ' s mind in his past self . The act of having a Time Lord inhabiting the body of his past self led to the universe beginning to break down . The cult convinced the younger Master that he had just been transferred into the body of his attacker - not identifying the attacker as his future self - and allowed the younger Master to depart . The past - in - future Master returned to his old prison and used a ' mind leech ' he had lured to the prison as part of an old plan to escape to try and restore his damaged mind , but although he was able to lure the Sixth Doctor into his trap , the Doctor was able to make a deal with the leech where it would only take his recent memories to restore the Master ' s mind , rather than taking his entire mind . ( AUDIO : " Vampire of the Mind " ) The Cult had intended to kill the older Master directly , but when he escaped their captivity , they hired the Transhuman Sisters of the Unholy Protocol and the Dragonhunter s to kill the older Master ; while the paradox would still damage the universe as the two Masters travelled around in each other ' s bodies , the death of the future - in - past Master would ensure that the damage was irreparable . After a period trapped in the 1980s , to the point where he spent twenty years trapped as a disembodied mind in his own TARDIS , the future - in - past Master was able to restore his body and escape after a confrontation with the Fifth Doctor . ( AUDIO : " And You Will Obey Me " ) The Seventh Doctor encountered both of the Masters and convinced them to return to their own bodies , although by this point the damage they had caused to space - time had become irrevocable . Leaving the Doctor on a spaceship that was about to crash , the two Masters then stole the Doctor ' s TARDIS and returned to the Cult ' s headquarters , where they killed all of the members . They planned to use the anomaly cage to recreate the universe , but were stopped by the Seventh Doctor - who escaped the crash in the Master ' s TARDIS , ironically using weapons that the Masters had used earlier and forgotten to reclaim from the Doctor - who made sure that the universe remained practically unchanged by its regeneration , his only change being to save the life of his temporary companion Jemima so that she was never killed by the Master . ( AUDIO : " The Two Masters " )