On Arrow Season 2, Oliver Queen (Stephen Amell) has rededicated himself to his mission of being more than just another vigilante, and is attempting to become a beacon of hope for the city’s most vulnerable, as The Arrow. In Episode 15, “The Promise,” Oliver is shocked when he learns that Slade Wilson (Manu Bennett) is not only alive, but that he has come to Starling City, while back on the island, Oliver, Slade and Sara (Caity Lotz) attempt to take over the freighter from Ivo (Dylan Neal), which turns into a huge battle. As everything changes in both present-day and the past, viewers will not only see Oliver put on the hood for the first time, but also Slade with the Deathstroke mask.

During this recent exclusive phone interview with Collider, executive producer/writer Marc Guggenheim talked about how “The Promise” is epic in scope and feels like a movie, why they wanted to shoot Oliver putting on the hood and Slade putting on the Deathstroke mask, each for the first time, in the same scene, why this episode is a game-changer for both the present-day and the past, how the Suicide Squad evolved, setting up potential further stories for them, who The Huntress will be now, when she reappears in Episode 17, and how they let the characters tell them where they’re going, especially when it comes to the romance aspect. He also talked about everything being on the table, when it comes to possible future cross-over between Arrow and The Flash, how terrific and outstanding the pilot script is, and that he’d love to write an episode of that show, as well. Check out what he had to say about Arrow Season 2 after the jump, and be aware that there are some spoilers.

Collider: It’s good to talk to you. You guys have been doing an awesome job this season. You definitely know how to do it right!

MARC GUGGENHEIM: Oh, thank you! We definitely appreciate it. Sometimes we’re not quite sure what we’re doing right, but it’s a fun show to do. It’s very challenging, but it’s also very fun. So, we really, really appreciate that. It’s that kind of feedback, frankly, that keeps me going.

What makes this next episode the biggest episode you’ve ever done? When you say something like, “It makes the season finale last year look like a student film,” do you worry about living up to that hype?

GUGGENHEIM: To be honest with you, I’ve seen that quote retweeted a bunch of times and I’m like, “Wow, I hope I didn’t oversell it!” I just watched the whole episode on the mix stage [on Monday], and I truly don’t believe I oversold it. I’d be very panicked, right now, if I had. It’s pretty epic. It feels like a movie. It just has a scope to it that we’ve just never had on the show.

What can you say to tease what we can expect from the story you’re telling in it?

GUGGENHEIM: It involves Oliver, Slade and Sara taking over Ivo’s freighter, in the past. We actually built the freighter, which is completely insane. It’s funny, when I pitched this episode to the production team, they said, “This episode is unproducable.” And the episode that you’re going to see [tonight] is exactly what I pitched. We didn’t cut any corners. Everyone put their heads together and figured out a way to do this episode. I have to give a lot of credit to J.P. Finn, our line producer, and Todd Pittson, our unit production manager. Glenn Winter, who directed the episode, did such an outstanding job. Glenn has always been one of our best directors, in terms of making every cent that appears on the screen look like a million dollars. It’s basically a huge movie on and underneath this ship, that involves pyrotechnics and explosions and gun battles. There are some shots in it that feel like they’re right out of Indiana Jones movie. I’m just really, really proud of it. I hope that it lives up to the hype, and if it doesn’t, I suspect that everyone will let me know. But, I’m pretty confident.

This episode also features the first time Oliver Queen puts on the hood, and the first time Slade Wilson puts on the Deathstroke mask. Was it important for you to shoot that contrast in the same episode?

GUGGENHEIM: Yeah, actually we wanted to do it in the very same scene, which is what we ended up doing. We actually debated that a lot, in the writers’ room. We were like, “Do we see Oliver put on the hood first, or do we see Slade in the Deathstroke mask first? And what do we want to end that particular act with?” I will say, in addition to the episode having a lot of production value and literal bang for the buck, it also is a game-changer for us, both in terms of the present-day storyline and the flashback storyline. And it’s not just Oliver and Slade having these iconic moments – though they’re certainly iconic moments – but with the way they’re shot and performed, you do feel like you’re seeing something momentous. But both storylines, in the past and the present, are game-changers, in the sense that the series will never be the same, with respect to both storylines. And the rest of the season has changed, from the perspective that there are genies taken out of bottles that you just won’t be able to get back in the bottle, once these revelations come out, and that obviously includes Oliver learning that Slade Wilson is alive and well and back in Starling City. It’s very hard for him to go back to his ordinary day job of being the Arrow with this huge threat looming out there. It’s a threat that’s not only expressed a willingness, but also an ability to harm the ones that he loves.

Having Deadshot on the show, and then adding Bronze Tiger, did you always know that you were headed toward the Suicide Squad, at some point?

GUGGENHEIM: That’s a great question. We started the year off with a list of characters who we wanted to see, and Bronze Tiger was one of them. Once we came up with an idea for how to do Bronze Tiger on the show, we very quickly did the math and were like, “You know, there’s Bronze Tiger, but Deadshot has also been on the show, and that’s already two members of the Suicide Squad,” and we realized that it was something that was possible. It wasn’t something that we backed into. We gave ourselves the freedom to go through Season 2 going, “You know what? If we organically build this group, then maybe in Season 2 or Season 3, we’ll get to see them.” But, we didn’t want to force it. One of the nice things about the Suicide Squad in Episode 16 is that it does feel very organic. It feels like it’s something that just came out very naturally from the characters and the storytelling that we’ve been doing, in the previous 15 episodes of this year. And even, quite frankly, playing with some pieces that we established last year, like the introduction of Lyla Michaels. It just has a nice feeling of completion to it, while at the same time, setting up potential further stories for the Suicide Squad. They’re a lot of fun together. It’s wonderful to see David Ramsey and his character of John Diggle interact with them.

What can you say to tease the return of The Huntress on the “Birds of Prey” episode? Who will she be now, when we see her again?

GUGGENHEIM: It’s been literally a year, in story time, since we’ve seen her. One of the things we told Jessica De Gouw, who plays The Huntress, was that we weren’t interested in treading over old territory with Helena. What we pitched her was the idea that basically Helena Bertinelli is gone. The only thing that remains is The Huntress. It’s been a year of her literally scouring the world to find her father, who was on the run at the end of Episode 17 of last season. We really wanted to show that wear and tear on her. We even aged up her costume a little bit, so you really get the sense that she has been traveling the world and literally has just spent a year killing people to try to get at her dad, and it’s done quite a number on her soul. We get to explore all that, in a really fun episode that also deals with Laurel Lance, in a very big way. One of the things we wanted to do with the episode was give Laurel her groove back, as it were. We have obviously taken Laurel down a very dark path, this year. As we started to see at the end of last week’s episode, she’s going to start turning the corner. And this episode with The Huntress is a very big move in that direction.

In setting up The Flash series, are you already thinking about possible cross-over between the two, or do you think you’d wait a bit before you did that?

GUGGENHEIM: Well, we’re fanboys and we always fantasize about, “Oh, we could do this cross-over. We could do that episode.” Everything is always on the table. I think it’s one of the things that’s made Arrow special. But we also all collectively feel like The Flash needs to stand on its own two feet, now that it’s gotten its launch from Arrow. I would say, as with all things, we trust our instincts to know when is the right time. Our compass has always just been our gut instinct. When the time is right, it will happen. Greg [Berlanti], Andrew [Kreisberg] and Geoff [Johns] have got to finish The Flash pilot first. There are a bunch of things that have to happen before we can start cross-pollinating shows.

Separately from the actors possibly crossing-over between shows, are you looking to write any episodes of The Flash?

GUGGENHEIM: Good question. Obviously, I would love to. Who knows what will happen? That would be a lot of fun. The Flash script is really, really terrific. It’s an outstanding pilot, and I know it will make a phenomenal series. Of course, it would be fun to work on any phenomenal series.

Are you surprised with how much fans are pushing for Oliver and Felicity to get together, especially when often the idea of two characters getting together is usually far more exciting than the reality of it?

GUGGENHEIM: You know, it’s funny. From my perspective, I think there’s a wide variety of fans out there. There are some people who really want Oliver and Felicity to get together. There are some people who want Oliver and Laurel to get together. There are some people who think that Felicity belongs with Barry Allen. Quite frankly, I’m just happy that the show can engender so many different opinions and desires on the part of the fans. Whenever you’ve got characters who have chemistry and who are flirting with each other, the way Oliver and Felicity have done, you think a lot about television history and the small number of shows that have actually managed to stick that landing. But with the possibility of Flash cross-overs, we’re very much instinctual writers and we go where the characters take us. Before we do anything, the characters tell us what they want to do, and we always try to listen to that.

Arrow airs on Wednesday nights on The CW.