Even before Supergirl was picked up by The CW for a second season, there was speculation about a four-way crossover between that show, DC’s Legends of Tomorrow, The Flash, and Arrow. Today, The CW revealed that the crossover is not only happening, it’s already in the works!

As reported by Comic Book Resources, The CW’s president Mark Pedowitz told reporters that “our annual crossover event this fall [will] be the biggest one ever.” Pedowitz declined to provide any details, but he seemed to infer that all four shows will take part in the network’s third annual superhero crossover event. But this will be the first time that the crossover will run four nights. Supergirl will remain on Monday nights, while Legends of Tomorrow will premiere on Thursdays in the fall instead of midseason. The Flash and Arrow are staying put on Tuesdays and Wednesdays, respectively.

Because Supergirl airs first during the week, the crossover event is likely to begin on that show before spilling over to the rest of the series. During the first season of Supergirl, it was established that the show takes place on its own Earth separate from the world shared by the CW’s previous DC series. Perhaps the crossover will come up with a reason to merge Supergirl’s Earth with its counterpart to make future crossovers easier.

The CW’s DC crossover is expected to drop in December before the midseason break.

What do you want to see in the four-way crossover between the CW’s DC shows? And who should be the villain of that story? Share your thoughts in the comment section below!

Image: DC Entertainment/Warner Bros. TV