The midseason episode of "Arrow" will be intense as Oliver McQueen faces off with the League of Assassins' notorious leader, Ra's al Ghu, all alone.

In last week's epic crossover episode, Team Arrow and Team Flash linked up in both Central City and Starling City to take down metahuman Ray Bivolo, who possessed power to cause people to lose control of their emotions. They also stopped ex-Suicide Squad member Digger Harkness from trying to kill Lyla with his deadly boomerang. Meanwhile, Felicity asked Caitlin to analyze DNA she recovered from the murder scene in Sara's death in the hope of finding her killer, reports Hypable.com.

The CW's extended trailer for the next episode, titled "The Climb," centers on Ra's al Ghul. In the preview, Oliver takes a trip to the mythical city of Nada Parbat to meet Ra's' at his home in the eastern mountains. He is seen climbing a steep mountain and then fighting with the dangerous villain without help from Team Arrow.

In another clip, Matt Nable's Ra's is seen fighting multiple assassins, and then executing one.

According to executive producer Marc Guggenheim, Ra's presence will have a lasting impression on the rest of the season.

"His presence changes the show," said the EP during an interview with Access Hollywood. "Literally, the show will not be the same after Episode 9. We always say, 'Our villains are the heroes of their own story,' and I think if you were to ask Ra's, he would say, 'I'm a pretty good guy.' In fact, he actually gives a speech in Episode 9 that kind of explains, 'I replace evil with death.' That's not such a bad thing."

Guggenheim went on to tease that fans will also get to see more of John Barrowman's character Malcom Merlyn in the rest of the season. He will also have a big role from Episode 10 and on and be featured in a flashback that will reveal his backstory.

"If you've been missing him, 2015 is your year," Guggenheim said. "In fact, I will say, even a little bit of 2014 because he has a very big role to play in Episode 9 as well, but wait 'til Episode 10. 10 and beyond, and we're going to be doing a Malcolm-centric flashback that will take you all the way back to basically when he sort of started down this dark path. You're gonna learn things about Malcolm that even Malcolm doesn't know, and it's going to big year for John Barrowman on the show."

The executive producer went on the say that viewers will see the similarities between Merlyn, a former League of Assassins member, and Ra's Al Ghu.

"You know, I think there's a reason why Malcolm and Ra's have very similar points of views on things and who knows, we may even see a little bit more of a connection between the two men in future episodes," Guggenheim said.

The official synopsis for "The Climb" reads:

"Nyssa (guest star Katrina Law) returns to Starling City and tells Oliver (Stephen Amell) that her father, Ra's al Ghul (guest star Matt Nable) has given Oliver 48 hours to find Sara's killer or the League of Assassins will start killing the citizens of Starling City. Laurel (Katie Cassidy) is stunned when her father (Paul Blackthorne) delivers a very special Christmas gift -- her mother, Dinah (guest star Alex Kingston). Meanwhile, Ray (Brandon Routh) tries to make amends with Felicity (Emily Bett Rickards) and Oliver sets a meeting with Ra's al Ghul."

"Arrow" Season 3, Episode 9, "The Climb," airs on Wednesday, Dec. 10 at 8 p.m. ET on The CW.

Watch the trailer below.

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