Exciting
An official synopsis has also been released which finally sheds some light on the mysterious series: “When heroes alone are not enough … the world needs legends. Having seen the future, one he will desperately try to prevent from happening, time-traveling rogue Rip Hunter is tasked with assembling a disparate group of both heroes and villains to confront an unstoppable threat — one in which not only is the planet at stake, but all of time itself. Can this ragtag team defeat an immortal threat unlike anything they have ever known?”
That explains those rumours about The Flash then, especially as that series has been dealing heavily with time travel thanks to the presence of the Reverse-Flash. It’s unlikely he’s the “immortal threat” reference above though. Some fans are speculating that it might be Darkseid, but he’s surely being saved for a movie.
DC’s Legends of Tomorrow is set to star Wentworth Miller (Leonard Snart/Captain Cold), Dominic Purcell (Mick Rory/Heatwave), and Victor Garber (Dr. Martin Stein/one half of Firestorm) from The Flash, along with Arrow stars Brandon Routh as Ray Palmer/the Atom and Caity Lotz, presumably returning as the deceased Sara Lance/The Canary. New additions to this world include Ciara Renee, Franz Drameh, and Arthur Darvill.