The serials The Deadly Assassin and Mawdryn Undead and the 1996 TV film would later establish that a Time Lord can only regenerate 12 times, for a total of 13 incarnations. This line became stuck in the public consciousness despite not often being repeated, and was recognised by producers of the show as a plot obstacle for when the show finally had to regenerate the Doctor a thirteenth time. The episode "The Time of the Doctor" depicted the Doctor acquiring a new cycle of regenerations, starting from the Twelfth Doctor, due to the Eleventh Doctor being the product of the Doctor's twelfth regeneration from his original set.