Elseworlds (Arrowverse)
"Elseworlds" is the fifth Arrowverse crossover event that features episodes of The Flash, Arrow, and Supergirl on The CW. The crossover event began on December 9, 2018, with The Flash, continued on Arrow on December 10, and concluded on Supergirl on December 11. "Elseworlds" introduces the characters Batwoman and Lois Lane, and the fictional Gotham City, to the universe. In the crossover, Green Arrow, Flash, and Supergirl, the former two having had their powers and lives switched, are drawn to Gotham City to confront Dr. John Deegan over his work at Arkham Asylum.
Source: Wikipedia
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