'The Flash,' 'Arrow' Stars Tease 'Ginormous' Crossover Battle, Romantic 'Clarity' and lebih 

\'The Flash,\' \'Arrow\' Stars Tease \'Ginormous\' Crossover Battle, Romantic \'Clarity\' and a Huge Bombshell!

Philiana Ng      7:25 AM PST, December 02, 2014

The CW\'s highly anticipated crossover event kicks off Tuesday with Oliver Queen and Co. making an unexpected detour to Central City, and

w star Stephen Amell has the perfect word to describe the epic two-night event.

"Crowded!" the 33-year-old actor tells ETonline. "It\'s a cool two hours of TV and it\'s fun to see new characters interact with one another. All in all, the whole thing\'s just a lot of fun."

But it won\'t be fun for Oliver and Barry Allen, who become foes in Tuesday\'s

, ominously titled "The Flash vs. Arrow," when the mentor-mentee square off in a heated battle.

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star Grant Gustin tells ETonline in previewing the first hour of the crossover. "He gets \'whammied\' by a metahuman."

As a result, the lovable, geeky Barry we\'ve come to know and love is gone and fans will meet "a completely different Barry," Gustin says. "It\'s why a ginormous fight between Barry and Oliver begins" -- creating one of the coolest TV superhero showdowns

Thankfully, Barry and Oliver won\'t be at odds for long. But it\'ll take this temporary rough patch to force them to address their dynamic as costumed colleagues, much less partners. "A lot of true, real things are said – issues between the two of them," Gustin says. "But they\'re able to move past it by the time it\'s all said and done. By the end of the crossover, we can say for the first time that they\'ve developed a mutual respect [for each other] and some type of a friendship."

who normally wouldn\'t interact with each other to get actual screen time together, which means one thing: comedy! "The biggest thing is to see just how funny it all is," executive producer Andrew Kreisberg tells ETonline. Diggle fans, you\'re in luck.

"When Diggle sees Barry in his suit for the first time using his powers, his reaction is my favorite thing in the world," Gustin says with a laugh. "How does Diggle deal with legitimate, other-worldly powers? It\'s funny," David Ramsey tells ETonline, sharing that it\'s Diggle\'s interactions with self-proclaimed fanboy Cisco that really takes the cake.

That\'s not to say that it\'s all fun and games during the crossover. When Team Arrow sets up shop in Central City, they take on the brunt of the digs, but when the STAR Labs crew visits Starling City, they get a cruel reality check. "They\'ll get a taste of the dark life Oliver and his cohorts lead, and maybe rethink why they need to take things a little more seriously," Kreisberg says.

As for Felicity, who\'s become a frequent Central City visitor, the crossover proves to be a tough balancing act. After all, she has complicated history of the romantic and professional kind with Barry and Oliver. "It\'s her being an adversary to the two of them and trying to keep calm. Felicity\'s sort of like, \'Okay, we\'re going to get through this and I have to sort these things between these two almost-stubborn gentlemen with these powers, these desires and these strengths.\' It\'s definitely not as fun for her," Emily Bett Rickards admits to ETonline.

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Amell won’t be the only one showing skin, Rickards says: "There\'s an emergency where she has to take her shirt off." What?!

crossover, it doesn\'t leave much room for romance. (Sorry WestAllen, SnowBarry, Barricity, Olicity fans!) But Amell has this to say about the future of Olicity after Oliver\'s ill-timed entrance at Palmer Industries, only to witness Felicity and Ray Palmer\'s kiss. "There is a little bit of clarity this week during the crossover in terms of how he\'s dealing with it," Amell hints. "And then, in a couple of weeks, some

– Oliver bombshell is dropped during the final minutes of

fans, make sure you don’t miss out! While we speculate as to what it could be (could it be Oliver\'s baby?), Amell and executive producer Marc Guggenheim offer clues.

"There aren\'t really any repercussions for Oliver," Amell says of the secret, hinting that there may be more than meets the eye. "It\'s more what the audience is learning." "If you watch the episode of

(Food for thought: Oliver\'s baby mama did presumably relocate to Central City after being paid off by Moira in season two.)

But seriously though, who wins the Flash vs. Arrow fight?

. While you\'ll have to watch to find out who gets bragging rights, Amell has his pick: "Diggle would win." Truer words have never been spoken.

begin their two-night crossover event Tuesday at 8 p.m. before wrapping up Wednesday at 8 p.m.

What are you looking forward to most? Who is your pick in the ultimate showdown: The Flash or Arrow? Sound off in the comments below!

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