Executive producer Marc Guggenheim tells THR: "We'll be doing something with Oliver and Felicity by the end of the year that will really confound and satisfy some viewers and infuriate others."

[Warning: Some spoilers ahead.]

Oliver Queen has met his match on Arrow.

His former mentor-turned-nemesis Slade Wilson returned from the dead at the end of last week's episode of The CW's comic-book drama and things between the two will be tense.

"That's the beauty of a cliffhanger is it has people wondering how you're going to get yourself out of this one," executive producer Marc Guggenheim tells The Hollywood Reporter with a laugh. "Episode 15 certainly answers that question in a very surprising way."

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Slade's desire for revenge against Oliver has been brewing for quite some time -- from at least episode nine -- but "the timetable and emotional motivation behind Slade's plan" comes to the forefront in Wednesday's episode, titled "The Promise." Guggenheim talks to THR about the aftermath of Slade's resurrection, Oliver's state of mind, another big "Olicity" moment and more.

Can you give us a preview of Wednesday's episode?

The episode is predominantly about Oliver, Slade and Sara trying to take the freighter in the past. We designed episode 15 to be like a sequel to episode 14 last year, where we flipped the paradigm and spent the majority of our story time on the island with Oliver and Slade. That was one of our most successful episodes last year and I think was one of the episodes fans responded to the most. We went into this year thinking we would love to do a sequel to that. "Go big or go home" -- we went very, very, very big and it feels like an epic little action movie directed by one of our DPs Glen Winter, who's directed some of our best episodes.

What is Oliver's state of mind at the moment?

The beauty of the revelation is it prompts Oliver to go through a variety of emotional reactions -- from shock to anger to fear to desperation to resolve. It's interesting for us to put Oliver through these various different emotional states, which you only get to do that if you have a really compelling, exciting incident in the form of Slade coming back to town.

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Now that Slade is in the fabric of Starling City, how does that change things for Oliver moving forward?

The truth is [episode] 15 is very much a game-changer for us because as you said, Oliver now knows that Slade is alive and in Starling City, and it really changes the entire season because now a clock is running essentially. Now that Oliver knows that his greatest nemesis is alive and back with a vengeance, it's very hard to go back to quote-unquote villain of the week episodes. Even though there are a couple of what people have been calling villain of the week episodes in our future, all of them now are imbued with a different sense of urgency and a different sense of anxiety because now this huge threat is looming out there. Even when Oliver has to deal with a non-mythology-related villain in a given week, he's always doing it against the backdrop of this looming threat that Slade represents. Nothing will be the same after episode 15.

Every decision that Team Arrow makes is magnified tenfold...

We'll be exploring it. It gets dealt with in episodes 15 and the episode afterwards, 16.

Is there an interaction between Slade and another character that may be surprising to viewers?

The one that always makes me smile whenever I see a cut of the episode is when Roy meets Slade and Slade meets Roy -- in part because of the way Colton [Haynes] and Manu [Bennett] play the moment. Because Roy having been injected with the Mirakuru back in episode nine, [he] has a connection with Slade. Slade has loomed very large in Roy's life ever since he was exposed to the Mirakuru. Oliver certainly mentions Slade quite a bit in episode 12 when he started training Roy. Watching the two of them meet face to face is a lot of fun and I think it's one of the high points -- there are a lot of high points -- but that is certainly one of them.

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How does Sara play into all of this?

She has also her own interesting history with Slade from their time on the island and what is most interesting for us as writers is that Sara, because of her time on her island, she knows Slade as well as Oliver does and know the danger that he poses. What's different is in the years that have passed since Lian Yu, she's become a completely different person, she's become a total badass, an international assassin who approaches Slade in a very different way than when she did back when she was a relatively innocent girl off the shores of Lian Yu. For me the fun of something like episode 15 is watching the difference between Sara in the past deal with Slade and Sara in the present deal with Slade.

Last week's episode featured a sweet moment between Felicity Oliver that made "Olicity" fans happy. Any more of those in the future?

(Laughs.) The fun or the agony of Oliver and Felicity is they're always taking one step forward and two steps back and that's what I meant when I said it was a slow burn. I will say by the end of the season, you'll see another big evolution of their relationship. But at the same time I don't want to spoil when and how that's going to happen. I do think part of the fun of the show and certainly Oliver and Felicity, things happen in the least expected ways. We'll be doing something with Oliver and Felicity by the end of the year that will really confound and satisfy some viewers and infuriate others but I think that's when you know you're taking chances.

It was established early on that Sara Lance's Black Canary is the first iteration, but as the series has progressed, has that changed?

The one thing that's always very safe to say with Arrow is never make assumptions. One of the little tricks that we have up our sleeves is we'd like to use the audience's assumptions to surprise them and twist things. All I really want to say on the subject of Black Canary is, there is absolutely a plan and you'll have to watch the show with some degree of patience to see how that plan gets unfolded. But we know exactly where we're headed and we hope that everyone will stay along for the ride.

Is Ted Kord -- whose company was mentioned in the most recent episode -- someone you'd like to bring in to the universe?

I'd love to. Over here on the show we have a great affinity for Ted Kord and the Blue Beetle, the character. For the time being, because of our affection for Ted, we're quite happy to at least have his company present in the show. (Laughs.) With continued good fortune, we will have many years on the year and many episodes and therefore many opportunities to continue to explore the corners of the DC universe.

Arrow airs Wednesdays at 8 p.m. on The CW.

Email: Philiana.Ng@THR.com

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