The show saw a major shakeup in Season 3: Professor Stein (Victor Garber) succumbed to injuries sustained during "Crisis on Earth X," Jackson (Franz Drameh) left the Legends to pursue a normal life, and The Flash's Wally West (Keiynan Lonsdale) joined the team full-time. Plus, in the finale, Amaya (Maisie Richardson-Sellers) again decided to return to her village, leaving the Legends behind for good (though Richardson-Sellers will remain a series regular).
According to executive producer Phil Klemmer, these changes were only the beginning. The show will continue to experiment with its rag-tag lineup of heroes next season with some potentially turning to the dark side, and a new face possibly joining the team. "There are more changes coming," he told TV Guide. "We don't want Legends to just remain in stasis. We're gonna have at least a legend, if not two, kind of breaking bad next season. And then, presumably, we'll find another new Legend along the way."
With Constantine (Matt Ryan) also joining the Waverider full-time, the show will head in a darker direction for Season 4. "We're probably going to lean more heavily into the world of myths and monsters," he said.
Legends hinted at this tonal shift in the season finale when Constantine popped up to inform the crew of a major problem. Their brilliant plan to release Mallus also opened the door for other mystical creatures to enter our world and now it's up to them to right that very big wrong. It looks like next season, the crew will be chasing after these dark threats.
And for those worried about the show diving into new genre territory, Klemmer maintained that Legends won't abandon its time-traveling roots. "We'll always be a time travel show but I think the genre thing really frees us up to do a lot of cool stories," he added.
DC's Legends of Tomorrow will return for Season 4 on the CW.
(Full disclosure: TV Guide is owned by CBS, one of the CW's parent companies.)