All the DC comics superheroes on TV are going to be on the small screen at the same time.

This week it was announced that, with the addition of Supergirl on the CW, the annual crossover event will include the heroes from Arrow, The Flash, DC’s Legends of Tomorrow, and Supergirl. Every year the CW has a big crossover event, but in the last two years, the crossover has only shown Teams Arrow and Flash joining forces. Previously, the crossover was a two-part event with the first part of the story taking place on The Flash and the second on Arrow. This year, The Flash (Grant Gustin) and Green Arrow (Stephen Amell)  joined together to confront Vandal Savage (Caspar Crump). This year’s crossover also introduced Hawkman (Falk Hentschel) and Hawkgirl (Ciara Renée) who have been regulars in the freshman season of DC’s Legends of Tomorrow.

Since DC’s Legends of Tomorrow premiered post-crossover event, this year would be the first time the heroes aboard The Waverider would team up with The Flash and Green Arrow. Now that Supergirl has switched from CBS to the CW, the crossover will go from juggling two series to now four.

Does this mean the crossover will span four episodes instead of two?

Entertainment Weekly reports CW chief Mark Pedowitz was already looking to the future for a very special crossover when Supergirl was picked up by the CW. “Just imagine what our superhero crossover episode is going to look like come December.” Later during the CW’s upfront presentation, Pedowitz confirmed the crossover event will be happening and it will be a really big deal. “Next season, Arrow, The Flash, Legends of Tomorrow, and now Supergirl will join forces in our annual crossover event, our biggest ever,” he said.

While this year will be Supergirl’s first on the CW, it won’t be the first time she’s met other heroes from the DC Universe. Earlier this year, The Flash crossed dimensions (and networks) for a special crossover event with Supergirl. The special appearance was intended to be a one-time deal, but now with Supergirl coming to the CW, she’ll be teaming up with other heroes as well.

The crossover event will air in December on the CW.