5. The Elixir Of Life
The Brain of Morbius gives viewers a further insight into the lore of the Time Lords and the wider Doctor Who universe by introducing us to the Sisterhood of Karn's Sacred Flame which, in turn, produces The Elixir of Life. The Elixir of Life, fans learn, allows the Sisterhood immortality. It is also discovered that the Sisterhood shares the Elixir with the Time Lords and that the Time Lords utilise the Elixir by making it a fundamental part of regeneration, thus negating the immortality inherent in taking the Elixir in larger doses. With the inception of the Elixir, fans are given another tasty morsel of Doctor Who lore. This tiny detail in the history of Time Lord regeneration gave Whovians everywhere another detail into which they could sink their collective teeth in order to speculate and theorise about the larger Doctor Who universe. The connection between the Time Lords and the Sisterhood of Karn is further strengthened when, near the end of the story, the Doctor has died with no hope of regeneration. The leader of the Sisterhood, Maren, bravely sacrifices the remaining Elixir to save the Doctor's life - something which was seen again recently, but more on that later...