The new season of DC TV shows is in full swing and with it the annual crossover special. The inclusion of Supergirl amps up the special to a whopping FOUR TV shows, an unprecedented number in television history. But if DC and the CW want to make history, then it’s gotta count.

Based on the dabbles of information given out so far, here’s everything you need to know about the upcoming special that combines Supergirl, The Flash, Arrow, and DC’s Legends of Tomorrow.

It’s based off the comic book storyline Invasion!

In 1988, former Marvel writer Bill Mantlo wrote his first book for DC Comics titled Invasion!, in which the war-mongering Dominators sought to harvest meta-humans for their own army. Among the races fooled into helping the Dominators were the Daxamites, Kryptonian colonists on another planet whom Mon-El descends from. In this week’s episode of Supergirl, Mon-El awakes from his coma and attacks Kara out of survival instinct.

The Dominators are for certain the antagonists of the upcoming crossover, but to what extent the storyline will adapt Invasion! remains to be seen.

It will be told in one multi-part episode across the four TV shows.

There are conflicting reports as to how long the crossover will be. Greg Berlanti told IndieWire it’s taking place across “three different productions” telling “one cohesive story.” He also confirmed that the totality of the crossover will be three hours long and “almost a mini-series.” He said, “Just today I was holding the three scripts back-to-back — that’s 180 pages of material.”

But Arrow star and social media maverick Stephen Amell said something different this week on a live Facebook broadcast. In the beginning of his stream, Amell said the special will be “five-different episodes of television.” Not five shows, he’s clarifies.

It could be a case of exhaustion or simple confusion on either Berlanti’s or Amell’s part, but the most that can be gleaned is that it’s going to a) include all the shows as expected and b) it’s going to take over an entire week of TV.

It begins with The Flash in November

Greg Berlanti confirmed the entire special, airing in November, begins in The Flash in Central City. “There are some characters who show up in Supergirl’s episode, but the story begins with The Flash episode and goes to Arrow and Legends of Tomorrow.”

It’s the 100th episode of Arrow and will feature the return of Deathstroke.

Arrow, the longest running show of the bunch, will reach its landmark 100th episode amidst the crossover. It would be a bum deal if Arrow didn’t at least try to steal the spotlight for its milestone when there are all these other shows hogging attention. Thus, Arrow will witness the return of fan-favorite villain Deathstroke.

Stephen Amell tweeted a hilarious picture of himself and Deathstroke on a park bench back in September while the filming of the special was underway.

In a separate tweet, producer Marc Guggenheim promised “No flashbacks,” meaning Deathstroke’s return isn’t just a memory of Oliver’s. But conspicuously missing was Deathstroke’s actor, Manu Bennett, who hasn’t outright confirmed if he’s reprising his role or not. He’s been coy on his Instagram, but that’s it.

Alert the shippers: Sara has a crush on Supergirl.

The real appeal of any good superhero crossovers Marvel’s The Avengers isn’t the explosive special effects and costumes. It’s the dynamic between all the sharp personalities. DC has excelled at this in its TV universe, with last year’s mediocre crossover still a lot of fun to watch.

Executive producer Andrew Kreisberg recently confirmed that Sara Lance, aka the White Canary on DC’s Legends of Tomorrow, might be a little more than interested in Supergirl. “Some people are instantly charmed by her. I think Sara’s [White Canary] got a little crush on her,” said Kreisberg.

Grumpy Green Arrow, meanwhile, will keep his distance from the Kryptonian. Kreisberg said Oliver’s arc in the crossover is his “breaking point” for accepting the bizarre and strange that exists in his universe. “He’s had Mirakuru soldiers and the Lazarus Pit and magic and Damien Darhk. Flying aliens who can incinerate you with their eyes? It’s one beyond the pale for him,” said Kreisberg. “He’s keeping his distance, which is a very Oliver thing to do. Kara sort of comments, ‘Does he not like me?’ and Barry’s like, ‘No, that’s kind of how he treats everybody.’”

Views.

A photo posted by Stephen Amell (@stephenamell) on

Expect more great reactions from Diggle.

Arguably the best thing that happens anytime Arrow has a crossover? Diggle’s reactions. His hilarious moment from when he met the Flash for the first time in the 2014 crossover is now a running gag: In the online-exclusive Superhero Fight Club 2.0, Diggle drops his Big Belly burger when he sees Henshaw become the Martian Manhunter.

The Flash Arrow Diggle
From "Flash vs. Arrow," the first part of the 'Arrow' and 'The Flash' crossover in 2014.

Now? It’s Supergirl who will astound him. Says Kreisberg: “There’s a moment where somebody says, ‘This is Supergirl,’ and they say, ‘What’s so super about her?’ and she just lifts off the ground. Digs like, I’m convinced.’”

It might begin November 15?

The crossover, confirmed to start in November, might air November 15. The only unknown episode title of The Flash that month is Episode 6, which occurs a week before “Killer Frost” (presumably when Caitlin becomes her supervillain alter ego). So, mark the calendars, just in case.

Photos via Reddit, The CW

Eric is a film and journalism graduate of Rutgers University. Specializing in the nerdy side of pop culture, he has also written for Geekscape and TheDishh. He’s still hoping to be bitten by a radioactive spider.