- For other uses of "Invasion!", see Invasion! (disambiguation).
Invasion! is the name of the third annual shared multiverse crossover event between , , and . The crossover aired over four nights from November 28th to December 1st, 2016.
Barry Allen investigates a meteor crash outside Central City which is a spaceship from which aliens emerge. Lyla Michaels tells the team that the Dominators had landed during the 1950s, but mysteriously departed. Barry assembles the original members of Team Arrow, Thea Queen, the Legends, and Kara Danvers, Supergirl of Earth-38. The team begins training at a S.T.A.R. Labs facility, sparring with Supergirl to prepare for the aliens. Kara struggles to earn Oliver Queen's trust, seeing that he’s is the most-respected among the heroes of this world. Cisco Ramon finds and reveals a message Barry's future self sent to Rip Hunter, which exposes Barry's manipulation of the timeline and its effect on other team members. As a result, only Oliver, Kara, Felicity Smoak, Martin Stein, Jefferson "Jax" Jackson, and Caitlin Snowstill trust Barry.
After the Dominators abduct the President of the United States, the team goes to rescue him; however, Barry remains behind since most of them distrust him. Oliver chooses to stay behind in support of Barry. Kara leads the group; they find the President, but the Dominators kill him when he is found and activate a mind control device to take over the group. The controlled heroes return and attack S.T.A.R. Labs, where Barry and Oliver confront them. While Oliver holds them off, Barry lures Kara to the device and manipulates her into destroying it, freeing everyone from the Dominators' control. When the team regroups, Ray Palmer tells Barry that everyone forgives and trusts him. Sara Lance, Ray, John Diggle, Thea, and Oliver are then abducted by the Dominators.
They are held in pods on a Dominators' ship, each one unconscious except for a shared hallucination of simulated reality. In the hallucination, Oliver is living at Queen Manor, having never gotten on The Queen's Gambit, and is about to be married to Laurel Lance. His parents are alive, and Diggle is operating as the vigilante the Hood. The captives begin seeing flashes of their real lives, and realize what the Dominators have done to them. Their escape attempt is blocked by personifications of their enemies: Malcolm Merlyn, Deathstrokeand two of his Mirakuru soldiers (who killed Ray's fiancée Anna Loring), and Damien Darhk and two of his H.I.V.E. soldiers. The adversaries are defeated, and the five awaken in the Dominators' ship and escape in a shuttle. Felicity, Curtis Holt, and Cisco try to hack into the Dominators' mainframe. Aided by Barry and Kara, they recover a device to locate the captives, who are rescued by Nate Heywood in the time ship, Waverider. Aboard the Waverider, Ray deduces that the Dominators were gathering information about metahumans, using the hallucination as a distraction, to help them build a special "weapon". Meanwhile, the Dominator mothership heads towards Earth.
Nate says that the first Dominator invasion occurred in 1951 in Redmond, Oregon. He goes there with fellow Legends Mick Rory and Amaya Jiwe and Felicity and Cisco to kidnap a Dominator for information. Although they are successful, the three Legends and their alien captive are taken prisoner by N.S.A. agents. The Legends learn from the Dominator that the aliens have arrived to assess humanity's threat, now that metahumans have appeared and formed the Justice Society of America. Felicity and Cisco rescue the Legends, and also set the Dominator free, carelessly altering history. In 2016 Central City, the team learns that the Dominators know about Barry's manipulation of the timeline, deem him a threat, and are demanding his surrender in exchange for peace. After the Legends return, the team discovers that the Dominators' weapon is a bomb that will kill all metahumans on Earth, with millions of collateral human casualties. The teams dissuade Barry from surrendering, and he and Cisco reconcile; Cisco realizes that continuing their estrangement would be hypocritical, as Cisco has now also changed the past. As Firestorm, Martin and Jax transmutes the bomb into a liquid, and the teams force the Dominators to retreat with a pain-inflicting nano-weapon developed by Martin's daughter Lily. As the heroes celebrate their victory, Oliver offers Kara his friendship; Cisco gives her a device which will enable her to interdimensional travel and communicate between Earth-1 and Earth-38. Martin persuades Jax not to tell the others that Lily's existence is the result of a temporal paradox he inadvertently caused when the Legends were in 1987.
- The crossover was marketed as Heroes vs Aliens.
- There are eight characters who appear throughout the entire "Invasion!" crossover (not counting "", which takes place entirely on Earth-38 and only sets up the story at the end of the episode). The characters are Oliver Queen/Green Arrow, Barry Allen/The Flash, Kara Danvers/Supergirl, Ray Palmer/The Atom, Sara Lance/White Canary, John Diggle/Spartan, Felicity Smoak/Overwatch and Cisco Ramon/Vibe. The only characters who appear in all the "Invasion!" episodes and "Medusa" are Barry, Kara, and Cisco.
- Notably, all eight of these characters are featured in the posters highlighting the event (shown below).
- Josh Segarra and Matt Letscher were the only series regulars who didn't appear in the crossover.
- This crossover is the first crossover to include and .
- Even though the crossover was marketed as a "4-night crossover event", the first part ("") didn't focus on the crossover until the last scene.
- However, at two different points throughout the episode, a breach suddenly opens and then closes, with the ending scene confirming that this was Barry and Cisco attempting to get to Earth-38. Furthermore, in portion of the crossover, when Cisco first opens a breach to travel to Kara's universe, he says, "This might take a few tries."
- This is the only crossover where all the main episodes share the same name: the name of the crossover itself, "Invasion!". Future crossovers will also include a number in every episode's title indicating which part of the crossover it is.
"To be continued on" cards
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