The Doctor goes back to his home planet to possibly fight the last biggest battle of his life.
For the 12th and final episode of "Doctor Who" season 9, the promo trailer shows the Doctor going on the war path and it will be a personal battle he will fighting. According to Entertainment Weekly, the Doctor finds himself back in Gallifrey, the planet he calls home. His mission is to destroy the Time Lords and he has traveled 2 billion years using his confession dial just to get there. He is out for blood and nothing can stop him. One of the Time Lords claims to have foreseen what the future holds and it looks like the Doctor is the prophesied hybrid who will destroy them. A Time Lord said, "The hybrid will stand in the ruins of Gallifrey and destroy a billion hearts to heal his own."
The teaser for "Hell Bent" also shows the Daleks and Weeping Angels who are all formidable foes of the Doctor in the past. There is also a short scene where a woman caresses the Doctor's hand and rumors are quickly circulating it could be the supposed to be dead Clara Oswald coming back which is kind of hard to fathom since her last scene pretty much leaves nothing to chance that she might still be alive.
In a report by Screen Rant, a hybrid is defined as a mixture of two warrior bloodlines which is capable of defeating the Time Lords. And given how much grief the Doctor has after the death of his companion Oswald, it looks like the prophecy might be right and it would mean he is prepared to purge anyone who comes in his path. Doctor Who already hinted in a past episode that he is half human and half Time Lord.
