Rattled by recent events, the Legends dive into work which finds them investigating an anachronism in a Viking settlement in the New World. The Legends realize that the Norsemen are worshipping an artifact as their god and are surprised by the artifact's origin. For the first time, Sara is worried that they might need back up when Damien Darhk shows up. Meanwhile, Jax finds a loophole that could potentially change history, but it is a risk he is willing to take.
Conclusion. Barry and Iris's wedding brings the gang together, but things go awry when villains from Earth-X attack the ceremony. All of the superheroes join forces to take on their most formidable villains yet. Earth's mightiest heroes–Green Arrow, Supergirl, The Flash and White Canary–lead their teams into battle to save the world.
With Sara out of commission, the team finds a new Anachronism that leads them to the jungles of Vietnam and right in the middle of the war. Ray, Amaya and Zari pose as journalists and trek through the jungle when they meet a time-displaced Gorilla Grodd. Meanwhile, Nate and Rory run into someone Rory knows, which give a glimpse into his past.
The Legends discover that the anachronism in 1930s Hollywood is a time-displaced Helen of Troy and she's just started a war between two film studios. As the Legends try to fix history and return Helen to the Bronze Age, things get complicated when they are blindsided by the appearance of a former enemy. Sara contemplates an offer she is made, which would make the Legends leave the anachronisms be. Meanwhile, Stein and Jax find themselves in an unusual predicament.
The Legends journey to London in 1897 to hunt down a time-traveling vampire. Once there, they run into Rip, but not everyone welcomes him back so quickly. Meanwhile, Stein discovers what Ray and Jax are up to and is not pleased.
The Legends learn that Ray Palmer will die because they broke time, so they race back to 1988 to try and save his life. When they arrive, they learn that young Ray Palmer has befriended a time-displaced baby Dominator, putting him in harm's way with the government and the Dominator's mother. New to the ship and missions, Zari must find her place and learn to trust the team. Meanwhile, Stein begins working on a secret project on the ship, which makes Rory and Jax suspicious.
Sara travels to the future to capture a rogue time traveler, but the Legends disrupt things by trying to protect an outlaw named Zari in order to hopefully lure in the time traveling assassin. Meanwhile, Stein tries to diagnose Amaya's condition, but Nate discovers an unusual treatment that Amaya begrudgingly agrees to undergo.
The Legends are in 1870 to fix the anachronism which happens to be at P.T. Barnum's fledgling circus. However, Nate and Ray accidentally free a saber-toothed tiger, creating a bigger problem. Meanwhile, P.T. Barnum is on the hunt to capture Nate and Ray to make his show even more exciting for the crowd.
The Legends are relived of duty by the Time Bureau when they break the timeline, as Season 3 begins. Meanwhile, Julius Caesar is spotted in Aruba, and Sara, Nate and Ray devise a plan to steal the Waverider back from the Time Bureau to stop Julius Caesar from conquering the modern world.