In a new clip from "DC's Legends of Tomorrow," which serves as the fourth and final installment in The CW's four-show "Invasion!" crossover, three members of the Legends put the Flash's plan into action. As seen in a behind-the-scenes featurette for the episode, Barry suggests sending the Legends back in time to kidnap a Dominator during the alien's first arrival on Earth back in the 1950s; that way, they can learn what the Dominators have been planning. The clip shows the Legends doing just that, and Heatwave is more than happy to oblige, especially if that means beating up a Dominator.

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Once in the “Arrow”-verse, Supergirl joined the Flash, Green Arrow, the Legends of Tomorrow and their friends in order to stop an alien invasion. With them, she faced down the Dominators, mind-controlling aliens who have grown so concerned about Earth’s metahuman threat that they have decided to stomp it out before it can reach the stars.

“The Flash’s” installment of the “Invasion!” crossover pit hero against hero after the Dominators mind-controlled Supergirl, White Canary, Heatwave, Spartan, the Atom, Firestorm and Speedy to turn on Flash and Green Arrow. Though Flash and Green Arrow were able to restore their friends to their original state, Team Arrow was abducted by the Dominators shortly thereafter, leaving Team Flash, the Legends and Supergirl behind to figure out how to rescue them.

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In “Arrow’s” installment, Team Arrow found themselves in a simulation where all their dreams had come true. However, this was not a kindness on the Dominators’ part, for they had tapped into their brains to discover vital information about the superhero resistance. Fortunately, they were able to break out of the simulation and hijack a space shuttle, only to be rescued by Citizen Steel and the Waverider.

Starring Melissa Benoist as the Girl of Steel, “Supergirl” airs Mondays at 8 pm ET/PT on The CW. The network is also home to Grant Gustin as the Scarlet Speedster in “The Flash,” airing Tuesdays at 8 pm ET/PT, Stephen Amell as the Emerald Archer in “Arrow,” airing Wednesdays at 8 pm ET/PT and Arthur Darvill, Brandon Routh and Caity Lotz in “DC’s Legends of Tomorrow,” airing Thursdays at 8 pm ET/PT.