MTV News visited the sets of "Arrow" and "The Flash" last week to talk all things CW superhero television — including the much-anticipated upcoming crossover between the two shows. This will not only be the second major crossover event of the Flarrow universe, but will set the stage for the "Legends of Tomorrow" midseason spinoff, so you better believe we're excited.

Here's what we learned about this "bigger," "crazier" crossover from the casts of both shows...

It will launch Legends of Tomorrow. ?

This isn't exactly breaking news, but it bears repeating. When chatting about the crossover, Danielle Panabaker (Caitlin Snow) told us: "It's bigger. It's crazier. The fact that [we combine] 'Flash,' 'Arrow,' and now adding in 'Legends?' It's nuts. But it's great."

And according to Stephen Amell (Oliver Queen), the crossover does a great job of melding these three shows together into one major television event: "In general, we’ve done an excellent job of weaving not just two shows, but three shows together. As always, it was logistically challenging, but I think when they’re finished, whenever that is, because there’s little pieces here and there to grab, I think that these … crossover episodes standing together will probably be, in my mind, the pinnacle achievement for both shows."

The cast will be even more expansive.

The Flarrow universe is racking up the characters, and — though not all characters will appear in the entire crossover event — that expansive cast will be well represented. According to Grant Gustin (Barry Allen): "It feels even bigger. I feel like more people are a part of it on both sides. We're tying in 'Legends,' obviously, so it's just bigger this year."

Amell also spoke on the scope of the upcoming crossover, saying: "When we started shooting 'Arrow,' there was just me, right? And then when they started 'Flash,' it was just Barry, and then obviously, the worlds expand... We shot a scene that had, like, nine superheroes in it. Nine people with either powers or super suits. It was an amazing thing to look at, to look out over the scene and see the world that has been built over the course of three plus years." ⚡➴ ?

Iris doesn't have much of a role in the crossover.

Sadly, Iris West (Candice Patton) won't be making much an appearance in the crossover storyline. According to Patton: "[Iris] is not involved at all in the crossovers that we have explored thus far. That doesn't mean we'll never see that. We know that crossovers have been extremely popular in our universe on the CW, so I'm sure we'll have more. But I will say, so far, in this season, she does not appear in any of the crossovers in a large way." ?

But it does include new "Legends" villain Vandal Savage.

Several of the crossover stars gushed about "Legends" big bad Vandal Savage who will be appearing in the crossover. Vandal is an immortal who has plagued humanity since the beginning of history and whom the "Legends" crew will be working on stopping across time. #AchievableGoals

"I'm working a lot with Casper Crump as Savage, and he's really good," Gustin said, while Amell stopped his answer to a general question about "Legends of Tomorrow" to say: "Vandal Savage, by the way, is a spectacular character."

The crossover will tell a serialized story.

While last year's big Flarrow crossover was structured so that fans of either show could watch regardless of whether or not they watched the other show, this year's crossover will be a more integrated story. According to Amell: "If you put them back to back on one night, they would run like one two-hour episode of television ... In fact, most of 'The Flash' episode takes place in Star City, and most of the 'Arrow' episode takes place in Central City."

In addition to the integrated elements that Amell teased, he confirmed that both episodes would share "a common villain," which certainly makes watching both "The Flash" and "Arrow" eps pretty necessary, if you want to get the whole story.

Barry is aware of Darhk.

Speaking of villains, though Gustin wouldn't say if he will share a scene with current "Arrow" big bad Damien Darhk (Neal McDonough) — or if he is the "common villain" in question — he did tease: "I will say Damien Darhk's name for sure." Yes, a pretty coy answer, but one that shows that Barry is at least aware of the mystical villain. And, given Barry's presence in the "Arrow" season premiere flash forward, you better believe we're looking for any and all clues that might relate to who is in that grave. ?

Barry will be super snarky.

In talking more generally about the Flarrow crossover, Gustin said: "I have more and more fun the more I do this character just because he's evolving more, he's getting closer and closer and closer to The Flash. Especially when I'm in the suit. Not necessarily Barry as much, but The Flash from the comics. Even when the stakes are really, really high, he's kind of just a smart ass, like having fun. It's almost like a defense mechanism now." Are you ready for more Snarky Barry?

We will get some fun new character interactions.

When chatting about the Flarrow crossover, Carlos Valdes (Cisco Ramon) teased: "One of my favorite parts about the crossovers is that, you get to see people that you wouldn't otherwise see interact, interact. And that sort of creates a mysticism, like fireworks, about it. So I think fans can definitely expect a lot of new relationships to blossom and new interactions to arise." Any requests?

We will see Caitlin and Felicity interacting.

Though Panabaker said that, sadly, she and IRL friend Katie Cassidy (Laurel Lance) wouldn't get any one-on-one character interaction in this crossover, she did tease some Caitlin and Felicity screen time, saying: "You do get to see a little bit more interaction between Caitlin and Felicity. Just little tiny bits of it. Those crossovers, it's a lot to pack into a 45-minute-ish episode." We gots to nab our Bechdel interactions where we can get it, we suppose...