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 band together with help from their super friends like Citizen Cold, The Ray, Felicity Smoak, Iris West and Alex Danvers 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.
Part 1 - Supergirl - S03E08
Part 2 - Arrow - S06E08
Part 3 - The Flash - S04E08
Part 4 - DC's Legends of Tomorrow - S03E08