If a Dalek saying, "the Doctor is regenerating" means nothing to you, then you best step away now. If it does, then get excited because there's a new trailer for "The Time of the Doctor," Doctor Who's Christmas special.
The Christmas special this year is a biggie: not only does it follow the splashy 50th Anniversary episode, but it's due to bid farewell to Matt Smith as the Eleventh Doctor, making way for Peter Capaldi as the Twelfth. The trailer shows some key baddies at hand: the aforementioned Dalek, the Weeping Angels, The Silence, the Cybermen. A new character named Tasha Lem, does factor into the trailer. She says "the siege of Trenzalore has now begun." (Here's a primer on Trenzalore.)
Capaldi, meanwhile, is really a non-entity in this trailer, though audiences got their first glance of him in the anniversary episode.