Maximillian Stael Maximillian Stael was the leader of a coven and a scientist who , along with Adam Colby and Thea Ransome , worked for Dr Fendelman in studying " Eustace " at Fetch Priory . He concealed his membership of the coven from his colleagues , including Fendelman , whom he was assisting in secret experiments , working with a time scanner . Biography . In July 1977 , a hiker was found dead in the woods adjacent to the priory . Fendelman asked Stael to " get on to London " and tell Hartman that he wanted a security team present within two hours . He also asked Stael to perform a post - mortem on the hiker ' s body . Stael discovered that the body was rapidly decomposing , as if the energy had been removed . He told Fendelman " all the binding force has gone and all that remains is a husk " . Ted Moss , a member of Stael ' s coven , visited him to warn him of the arrival of the Fourth Doctor and Leela , telling him that they " know all about us " . Stael said he would deal with them and asked if their friends were prepared . Moss said they were waiting for the word . Stael told him that , when the time came , they must be twelve , but Moss disagreed , telling him " we know you lead the coven now , but we know the old ways . Thirteen be the number " . When he had gone , Stael spoke to himself , saying " a place must be left for the one who kills . " When Stael found Thea in Fendelman ' s lab , he told her it was fitting she should be the key to his power - a link between her and the Fendahl having been created - and , declaring her the " chosen one " , he drugged her with a cloth pressed over her face . When she woke , Thea was in the cellars of the priory . Stael told her she would be " the medium through which the ancient power of this place is focused " and that , through her , he would " conjure and control the supreme power of the ancients " . He then injected Thea so that she would sleep . Before the drug took effect , she called him a fool , to which he responded : " I shall be a god . " Returning to the lab , Stael used a gun to threaten Fendelman and Colby , ordering them to turn off the time scanner as he was not ready ( TV : " Image of the Fendahl " ) — this incident was witnessed by the Eighth Doctor as he fell through the time fissure enhancing Fendelman ' s time scanner . ( PROSE : " The Taking of Planet 5 " ) After Colby turned off the scanner , the pair were bound to pillars in the cellars of the priory , next to where Thea was laid out on a pentagram on the floor . Fendelman asked Stael how long he had been planning this , and he replied that it was ever since Martha Tyler ' s vision began to come true . Colby mocked him , calling him " an occult freak . One of those feeble inadequates who thinks he communes with the devil . " Stael replied " unlike you , I am not a crude lout , Colby . The grimoires do not impress me . Mrs Tyler ' s paranormal gifts and the race memory she draws on , these were the signposts on the road to power . " He told Colby he looked forward to his terror . Stael placed the skull , Eustace , on an altar and connected it to the time scanner . The members of the coven gathered around the prone Thea . Realising his intent , Fendelman warned him not to carry out his plan , telling him that " mankind has been used . " Stael shot him dead . The ritual began and Thea was transformed into a Fendahl core . She set about killing members of the coven as Stael protested " this is not how it should be " . The Doctor and Leela went into the cellars and freed Colby . The Time Lord tried to help Stael to escape but , having looked into the eyes of the transformed Thea , he could not move . Stael asked the Doctor to hand him his gun from altar . The Doctor told him it would have no effect on the core , and he replied that it was for him , not her . Having given him the weapon , the Doctor left the cellars , and Stael shot himself . ( TV : " Image of the Fendahl " )