"DC's Legends of Tomorrow" have never been afraid to bend the rules. In their quest to protect the integrity of the timeline, they've had to go to great lengths in order to stop time aberrations. However, thanks to their new circumstances, they'll have to "break a major rule" in order to save the world.
“We’re going to do the one thing on the show we said we would never do,” executive producer Marc Guggenheim told Entertainment Weekly. “Without spoiling too much, clearly they’re going to have to do something very significant and break a major rule in order to fix things.”
As to what rule they'll break, Guggenheim didn't clarify. Perhaps fortunately for the Legends, though, the rules just changed. At the end of "Fellowship of the Spear," the last episode, the Legion of Doom successfully procured the Spear of Destiny, which the Legends had made whole. Using the Spear, they altered reality, fashioning it after their wildest desires.
Seeing as the Legion has changed reality, not time, the Legends will likely have to go to drastic measures in order to put a stop to their evil plans. Perhaps, in an effort to circumvent these changes, they will have to go back in time and cause an aberration in order to save reality itself. However, until the finale airs, there's no way to tell for sure.
According to the official synopsis for “Doomworld,” the penultimate episode of Season 2,
BETRAYALS – After obtaining the Spear of Destiny, the Legion of Doom rewrites reality, leaving the Legends changed, perhaps forever. Frightfully, the Legends’ and the world’s hope rests with Rory (Dominic Purcell), but being the “hero” is not easy for him. Meanwhile, there is tension within the Legion of Doom and the reason why the Spear of Destiny needs to be destroyed is revealed. Victor Garber, Brandon Routh, Arthur Darvill, Caity Lotz, Franz Drameh, Nick Zano and Maisie Richardson-Sellers also star. Mairzee Almas directed the episode written by Ray Utarnachitt & Sarah Hernandez.
Airing Tuesdays at 9 pm ET/PT on The CW, “DC’s Legends of Tomorrow” stars Brandon Routh as the Atom, Victor Garber and Franz Drameh as Firestorm, Caity Lotz as White Canary, Maisie Richardson-Seller as Vixen, Dominic Purcell as Heatwave and Nick Zano as Citizen Steel.