During tonight's episode of Black Lightning, The CW debuted a new trailer for next week's Arrowverse crossover event "Elseworlds." Unlike the others, it's much longer and offers more of what to expect from the 3-night spectacle.

As established in earlier previews, Oliver Queen and Barry Allen have swapped lives; Oliver is the Flash and Barry is the Green Arrow, and their respective teams are unaware of the switch. Thanks to the Monitor, who has already caused chaos in another universe, reality has been rewritten by Arkham Asylum doctor John Deegan. And if you thought Ollie and Barry switching lives was weird, there's even more to come.

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Eventually, the duo and Supergirl will make their way to Gotham City, where they'll meet Ruby Rose's Batwoman. She will show up during the Arrow portion of the crossover, before her solo series debuts in 2019. Beyond Batwoman, there's also a look at John Wesley Shipp returning as the Flash from his 90s series, the book that Deegan uses to rewrite reality, Superman in his Black Suit and possibly the villainous android Amazo. All of it must be undone to avoid the "Crisis" that's said to be coming.

This year's Arrowverse crossover event will involve the casts of Supergirl, Arrow and The Flash. The event will unfold over three nights, starting with a special episode of The Flash on Sunday December 9 at 8 pm ET/PT. Then, it continues Monday, December 10, with Arrow, and concludes on Tuesday, December 11, with Supergirl.