is the third Arrowverse crossover event, with episodes of the television series The Flash, Arrow and Legends of Tomorrow on The CW, and is inspired by the 1989 comic miniseries Invasion!.

As a result, only Oliver, Kara, Felicity Smoak, Martin Stein, Jefferson "Jax" Jackson, and Caitlin Snow still trust Barry.

After the Dominators abduct the President of the United States, the team goes to rescue him, with Barry sitting the mission out and Oliver staying behind in support of him.

Their escape attempt is blocked by personifications of their enemies: Malcolm Merlyn, Deathstroke and two of his Mirakuru soldiers, who killed Ray's fiancée Anna Loring, along with Damien Darhk and two of his H.I.V.E.

Aided by Barry and Kara, they recover a device to locate the captives, who are rescued by Nate Heywood in the Legends' timeship, the 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".

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.

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.

As the heroes celebrate their victory, Oliver offers Kara his friendship, and Cisco gives her a device which will enable interdimensional travel and communication between Earth-1 and Earth-38.

Martin persuades Jax not to tell the others that his daughter Lily's existence is the result of a temporal paradox he inadvertently caused when the Legends were in 1987.

[15] He expanded on the difficulties, saying that "built-in shut-down days" for Supergirl were not planned on, in part because the series switched from CBS to The CW, and that this inability to shut down normal production prevented it from having a larger role in the crossover.

[18] The following month, Arrow and Legends of Tomorrow creator and executive producer Marc Guggenheim said that the title of each episode of the crossover would be "Invasion!".

Guggenheim added, "In the midst of time travel and aliens, it was just one sci-fi problem too much" and conceded that "if people at the studio were confused by the script, it was probably not particularly friendly to casual fans.

[23] When the Dominators were chosen as the threat for the crossover, the writers were able to justify the heroes' uniting; since Supergirl "is knowledgeable about these particular enemies, the Legends can help better understand the last time the Dominators visited Earth thanks to their time travel capabilities, and both Teams Flash and Arrow have a diverse array of capable heroes who are able to understand and counter just about every imaginable threat.

[28] Colin Donnell and Colton Haynes appear as holograms, reprising their roles as Tommy Merlyn and Roy Harper, at the end of the Arrow episode.

[31] A faux classified U.S. government video was released, set about 70 years in the past, detailing the Dominators' first attempt to conquer Earth.

Club said that the episodes did "admirable work advancing the overarching narrative while maintaining each show's distinct perspective" along with being "a hell of a lot of fun, and it's significantly expanded the scope of the Arrowverse by bringing in an extraterrestrial enemy ...

Part of that is creative—it would have been better to get a fuller understanding of who these beings really are and how they're able to know the long-term effects of Flashpoint; plus the resolution seems awfully pat ... and lacks the resolutionary scope that was expected."

[2] Collider's Allison Keene enjoyed the interaction of the cast members between the four shows, with The Flash setting the tone of the crossover, with the others incorporating "its light-hearted, witty banter and a fast-paced action and editing".

Schedeen appreciated the focus on the fallout from Flashpoint, calling it "one of the biggest flaws of Season 3 so far" on The Flash, and hoped that more of the Dominators' comic backstory would appear in the crossover's other two episodes.

Von Doviak questioned some of the episode's events, such as Barry's knowledge of the Legends adventures and his not caring about secret identities, and said that viewers "who don't necessarily follow the other three shows religiously are at a disadvantage".

could have been "an unholy mess" trying to fit Arrow's 100th episode celebration in the middle of the crossover, by focusing on Arrow's past and including former cast members "ends up giving the show a way to develop the power and the threat of the Dominators without this crossover just being three straight episodes of heroes and aliens punching each other."

Burt felt the shared hallucination "works because of the performance of all of the actors (including many returning ones) and the sentiment that this show has genuinely inspired in people."

[60] Sara Netzley of Entertainment Weekly gave the episode an A, saying, "We get enough cross-team action to make it a treat for viewers of the Berlanti-verse while still forwarding the "Invasion" story line—and honoring the characters, plots, and themes that have made Arrow such a satisfying show over the last four and a half seasons.

And even if there were a few points of frustration (mainly involving a lack of Supergirl early on), it made the most of the premise and delivered a rousing final battle."

He enjoyed the final back story of the Dominators, which gave them clearer motivations so they no longer felt like "a completely faceless, generic alien threat", and Cisco's creation of a device for Supergirl to travel between universes, which would allow for more frequent crossovers between the characters.

He called the final battle "anticlimactic", noting it would have been more satisfying if there was a "more creative use of all the different powers in this group working together, and... a stronger sense of collaboration among the human/metahuman fighters.

Li also added that the "budgetary constraints were glaring", and gave as examples Thea's failure to appear in the episode and Kara's absence from the confrontation with the elderly glasses-wearing official after Oliver lashed out at her.

Despite this, Li felt much of the episode worked, with each character getting a chance to shine "and though the Dominators' motive [was] still somewhat muddled, the invasion sparked fun rapport among the teams...