Tonight ends Invasion!, the four-show, three-night crossover event that took over The CW's DC Universe of superhero shows, pitting "heroes vs. aliens" -- even as one of the network's main heroes, Supergirl, is an alien herself.
And since her universe also has Dominators -- as revealed on Tuesday's episode of The Flash -- it seemed like after she helped Green Arrow and The Flash turn back an invasion of the ugly-looking spuds, it was only fair she has some means to contact them once it's all through.
Enter Cisco Ramon's interdimensional extrapolator, which allows Supergirl to approximate some of his Vibe powers and open a small dimensional rift -- known as a breach -- that means she can reach out and touch someone on Earth-1 anytime she wants.
"Obviously they've gotten to the point where we wanted to make that a little bit easier," executive producer Andrew Kreisberg said of the crossovers. "The next time we do it, it certainly means it doesn't necessarily have to be because Oliver and Barry need Kara. It could be because Kara needs them. Again, we don't have anything planned. We just barely survived this one. We're not too concerned with what we're going to try to do next year. It just gives us as storytellers another way to come at a story."
Arrow, The Flash, and Supergirl will cross over with DC's Legends of Tomorrow this week in "Invasion!" a three-part crossover that starts in the final moments of an episode of Supergirl and then plays through the other series. Based on the 1988 comic book event miniseries Invasion! from Keith Giffen, Bill Mantlo, Todd McFarlane, Bart Sears, and the crossover -- with its marketing title "Heroes vs. Aliens" -- will closely track the plot of that storyline: aliens will be assembled by The Dominators and descend on Earth to bring an end to the "threat" of Earth's burgeoning metahuman community.
In the comics, the Dominion were secretly hoping to build their own super-race, and as a result created a handful of new superheroes in the course of the story.
NEXT: The Flash, Arrow, Supergirl, Legends of Tomorrow Crossover Trailer / First Look At The Dominators / Invasion! Crossover Promo Photos / Potential The Flash Spoiler Spotted On Set / Will Joe West Die During The Invasion! Crossover? / Enter To Win An Ultra-Rare Invasion! Crossover T-Shirt
Supergirl airs Mondays at 8 p.m. ET/PT; The Flash on Tuesdays at the same time; Arrowon Wednesdays and DC's Legends of Tomorrow on Thursdays. All four series air on The CW. The "Invasion!" crossover will air beginning November 28.