Arrow's executive producer, Marc Guggenheim, discussed what to expect from the rest of the second season and suggested that nothing would be the same after episode 15, in a recent interview with The Hollywood Reporter.

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The preview of episode 15, The Promise, of season 2 of Arrow revealed that Slade is back and he is out to get Oliver's blood.

Guggenheim said that the episode would be a "game-changer" and suggested that Slade would probably be the biggest of villain and threat of all.

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"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." he said. "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."

The producer went on to suggest that the plot and storylines in the show would really be affected by this sudden turn of events.

"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," he said. "Nothing will be the same after episode 15."

In last week's episode Felicity and Oliver seemed to share some sparks. The producer weighed in on how fans could expect that relationship to develop. He suggested that their romance had been moving along very slowly thus far but a "big evolution of their relationship" was in store.

"I do think part of the fun of the show and certainly Oliver and Felicity, things happen in the least expected ways," he said. "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."

Here's the official synopsis for the episode:

Here's the official synopsis:

"Oliver is shocked when he learns that Slade (Manu Bennett) has come to Starling City. Back on the island, as Oliver, Slade (Caity Lotz) prepare to take over the freighter from Ivo (guest star Dylan Neal), Sara pulls Oliver aside and tells him he needs to kill Ivo to prevent him from telling Slade what happened with Shado. Oliver feels immense guilt over the situation but realizes Slade's growing rage from the Mirakuru makes him unpredictable and he could turn on his friends if he thinks Oliver is to blame. Oliver agrees to kill Ivo and the battle begins."

The Promise will air on March 5 at 8 p.m. on CW.

Watch the clip here:

Tags: Arrow