We are less than a week away from "Crisis on Earth-X," the DC crossover airing Monday and Tuesday on The CW -- and Supergirl star Melissa Benoist will be heading to Earth-1 to attend a wedding and kick some Nazi doppelganger butt.

The story will bring together the casts of Supergirl, The Flash, DC's Legends of Tomorrow, and Arrow to fend off an invasion fromEarth-X, a universe where the Nazis won World War II. It is not yet clear why they attack, but one thing is for sure -- with a dark doppelganger of Supergirl on their side, things can get ugly pretty quick.

During a recent set visit, Benoist spoke with reporters about her role in the story.

What can you tell us about this year's crossover? Chyler teased that she'll be going with you and what's that look like having her by your side?

I always wished that she had been by my side for every crossover that I've done, because they are always so massive and such undertakings workload-wise.

I said to myself at the end of last year's crossover, "There's no way it could get bigger than this. How are they going to write something bigger than this? Well, they wrote something massive that was overwhelming to read, in an exciting way of course, but also at the same time like I had to brace myself. I think we all did. Everyone goes to Central City to Iris and Barry's wedding, but of course it's the comic book world so not every wedding goes as planned. You'll have to see, it's pretty crazy. They get some really evil visitors from Earth-X.

You get to wear a different costume in the crossover.

I did play two characters. I did wear a very different outfit. There's still a cape and my face is covered and she's not so nice. It was pretty challenging.

I've done here and there, I've had moments like that on this show with Bizarro and when Martian Manhunter takes over Kara's body, but this was entirely different. This was not even Red Kryptonite-isque. This was way worse.

Was that difficult to play?

Yeah, especially when we do motion control shots where I have to be in the scene with myself and it's more tedious than a traditional split screen. And essentially, you're memorizing a whole scene, every line, every bit of dialogue and I didn't anticipate how hard the transition would be to go from lightness to darkness. A fun challenge.

"Crisis on Earth-X" is a four-hour event that will air on November 27 and 28 beginning at 8 p.m. and running for two hours each day; Supergirl (8 p.m. Monday), The Flash (8 p.m. Tuesday) and Legends of Tomorrow (9 p.m. Tuesday) will remain in their normal time slots but Arrow will move from Thursday to a 9 p.m. Monday placement for the week.