The Arrowverse isn't just going elsewhere, it's going "Elseworlds."

The CW released a new poster for its annual DC crossover event, which will tie together "Arrow," "The Flash," and "Supergirl" over three nights this December. The poster revealed the event's title: "Elseworlds."

That's a nod to a special imprint of titles that took place outside the regular DC universe (like one in which Batman hunted Jack the Ripper in Victorian-era England).

The poster also teased the Bat logo, since the event will take the heroes to Gotham, where they're introduced to Batwoman (Ruby Rose).Cassandra Jean Amell has also been cast as Nora Fries, the wife of famous Bat-villain Mr. Freeze.

Tyler Hoechlin is also reprising his role as Superman, and fans will get to meet Lois Lane (Bitsie Tulloch). And LaMonica Garrett ("Designated Survivor") will play Mar Novu aka The Monitor, “an extraterrestrial being of infinite power.” In the comics, Monitors intervened in crises in the Multiverse.

The Arrowverse crossover event will air Sunday, Dec. 9 through Tuesday, Dec. 11,