Last year’s Arrowverse crossover – titled “Invasion!” – was already a pretty huge affair, but this fall’s “Crisis on Earth-X” event promises to be even bigger. On top of having the cast seeing double when they come up against their Nazi doppelgangers from another Earth, one of the stars has revealed the whopping amount of heroes who’ll take part in the crossover.

Ex-Superman actor Brandon Routh – who plays Ray Palmer/the Atom on Legends of Tomorrow – revealed a highlight of his that will occur in the event during a recent set visit. He announced that one scene in particular will see the united heroes of the Arrowverse come together on the bridge of the Waverider. And there’s going to be a heck of a lot of them.

“I have a limited adventure in the crossover, but I do get to work with a few people that we had a good time. The best thing that we got to do was the big gathering of everyone here in our world, on the Waverider, which was pretty awesome to have all of those superheroes together, and it was a really unique and fun thing which I think the audience will like as well.” “We used to get upset about have nine characters on the bridge and figuring out how to shoot that, but having 21 or whatever it was is pretty insane. But Greg Smith, who was our director for our episode, knew what he wanted pretty quick. You have to have your ducks in a row when doing a crossover because people are coming from four different shows, like ‘We have Melissa for 2 hours and we have Grant for an hour, and we have Stephen for 30 seconds,’ so you’ve gotta get the shot!”

That’s right, according to Routh, over 20 heroes will come together during a single scene. Beat that, Justice League!

So, who could those characters be? Well, those confirmed to appear already take the number up to 18. Namely, Supergirl, Flash, Green Arrow, Atom, White Canary, Zari, Killer Frost, Vibe, Black Canary, Wild Dog, Heatwave, Firestorm (Jax and Stein), Steel, Mister Terrific, Vixen, Wentworth Miller returning as Captain Cold and new addition The Ray (Russell Tovey). It’s not too far-fetched to imagine Martian Manhunter joining in on the fun as well. And once you factor in supporting characters like Alex Danvers, Felicity Smoak and John Diggle, 21 heroes doesn’t seem that ridiculous.

“Crisis on Earth-X” unites the Arrowverse in just 11 days time. It kicks off on Monday, November 27th, with Arrow and Supergirl and is concluded the following evening with The Flash and Legends of Tomorrow.