[Warning: This story contains spoilers from the season six finale of HBO's Game of Thrones, "The Winds of Winter."]

Orchestrating a wildfire attack is hard work, even if Cersei Lannister (Lena Headey) makes it look like a walk in the park.

The opening minutes of Game of Thrones' sixth season finale center on Cersei obliterating her enemies with fluorescent fire, a plot that slowly unfolds over the course of 10 tense minutes. She destroys the Sept of Baelor with a carefully placed, slow-fuse batch of wildfire, incinerating Margaery Tyrell (Natalie Dormer), the High Sparrow (Jonathan Pryce) and more. Away from the flames, children stalk through the dark, gruesomely stabbing Grand Maester Pycelle (Julian Glover) to death and wounding Lancel Lannister (Eugene Simon) as well. All this plays out as the characters at Cersei's trial gain more and more information about their dire circumstances — too little too late. The ensuing fireworks serve as an explosive payoff to the season's deliberately paced King's Landing story, and sets the standard for everything else that unfolds during the finale.

Among the many architects of the wildfire sequence, Game of Thrones composer Ramin Djawadi cannot be overlooked. He created a new piece of music, called "Light of the Seven," specifically for the scene. In the days leading up to the finale, Djawadi's social media presence was relatively quiet: "I started Twitter maybe three or four weeks ago, but when the finale aired, my Twitter account blew up." Interesting choice of words …

Here's what Djawadi told The Hollywood Reporter about composing "Light of the Seven," the new instrument it introduced to Game of Thrones' musical language, and more.

What were your initial ideas in approaching this piece?

The interesting thing to me was the use of the piano. When we started the season, [showrunners David Benioff and Dan Weiss] and Miguel Sapochnik, the director of the episode, reached out to me and said, "There's something coming up in episode 10." We talked about "The Light of the Seven," and how it needed to be a new piece of music. Any kind of character theme could tip it, and we didn't want to tip the audience. Miguel brought it up: "What about the piano?" We discussed it. The piano is not really in the language of the Game of Thrones score. We went back and forth about it, and then we came up with the organ, which we used last season with Cersei during the atonement walk and some of the other scenes when she's in prison. But the piano was the new instrument. What I love about Game of Thrones is that it's a fantasy show and fantasy world, and already in the history of the show, I've run wild with instrumentation. There's modern synthesizers in it and all kinds of things. So why not? Let's have the piano. It'll be a big surprise, and it's what we want to achieve. And there's really nothing like it. The piano has this decay and attack at the same time. We even experimented with the harp, but the harp was not as haunting as the piano.

The piano plays in a versatile way, as well. The sequence builds from the audience and characters having little information, to having all of the information — for most of them, a bit too late. It lines up with the piano's quieter points, gradually becoming stronger in moments of revelation.

Exactly. The piano has a huge dynamic range that almost no other instruments have. It can play very low and it can play very high. It has the attack of the note and the long decay of this haunting feel. It all felt like a perfect fit. What's great about the scene, too, is there's hardly any dialogue. It's nine minutes long. I knew I had to start minimal and give it space. Let notes ring, then give it space, and build up the anticipation from there, without tipping in either direction. You want to watch the scene and slowly realize, "Wait, what are these kids doing here? And what's this?" And you see the wildfire dripping. You start putting things together, like, "Wait, what's going on?" It was very fun to build. We have organ in this, we have cello, we have solo violin. The big orchestra, the strings, don't even come in until the very last minute or so of the piece. It was so tempting to start earlier, and make it blow up earlier, but I felt like it would be nice to wait until you see the visual of the wildfire and you realize what's going on.

Game of Thrones isn't going to have a digital clock on its nuclear bomb like you would see in 24, for instance, but the strings signal the final countdown until the boom.

Right, exactly. It was an amazing opportunity to have a long sequence that can carry music like this. In the history of Game of Thrones, there's also a lot of sequences that are without music. The show is very well spotted with where music comes in and where it doesn't come in. Very rarely do we have these long pieces of music like this. This season I think we had it more than in any other season, even the early episodes, like the Hodor scenes [in "The Door"], that's a 10-minute section with all music and very beautiful shifts within. And the "Battle of the Bastards" as well. That's a 22-minute sequence.

The vocals come in right as the children start drawing their knives to attack Grand Maester Pycelle. Can you track the origin of that idea?

This comes back to when we started talking about it conceptually. "What about the piano? What about the organ?" I said, "Well, what about these kids? We have these kids running around. What about solo vocals? Boys' vocals?" So when these vocals come in, that's when you see the knife. We thought the voices added another level of this haunting experience. It's two boys, that's it. Not a big choir. It's two solo boys singing.

It's only two? It sounds like a group!

It's two boys and they sing in unison, which might be why it sounds bigger. And every once in a while, they hit a note where they don't sing the same note, and it creates this tension. That's also intentional. You want this jarring feeling, that there's this unison line, but then it kind of departs, and then comes back together. That was the idea behind that, to enhance that tension.

The organ bursts in around the time of Pycelle's death, then quiets for a beat while Lancel Lannister is in the dark, calling out for the child. It returns once he's stabbed by the boy, and shifts into a version of the Game of Thrones theme.

That's right. The scene carries us through a lot of different moments happening at the same time. Certain characters are a little bit ahead of others at certain times. When it cuts to Lancel, he doesn't know yet about the stabbing in the other location, so he's still looking around and wondering why he's still following this kid, and what's going on. Then he gets stabbed, and the organ kicks in again. And yes, I do play the main theme there. I felt that it's such a new piece of music, and it is piano, that I didn't want us completely going away. I wanted to make sure people heard the main theme and knew it was still Game of Thrones. That's what's nice about the main theme. We always look at it as an overall blanket for the entire show. We can use the theme for any kind of plot or moment. That's why I thought it worked well there, and it does come back again for a second time, right before the explosion, with the big strings.

It's an interesting point about not wanting to reveal any character themes; once you hear "The Rains of Castamere," for instance, you would know this was a Lannister plot.

Exactly. That's exactly right. We knew right away we couldn't play a Lannister theme, because even though the scene is about her and her trial, it would put too much in her court. Especially when everyone's observing, "She's not here …" It would have said to people that she's up to something, right away. So we made this conscious decision to have a new piece of music that's very minimal in the beginning, so it feels like everyone is waiting on something, and we don't know what it is.

Were you charting specific individuals' journeys throughout the scene — such as applying changes to the piano as Margaery's sense of danger builds?

Yes and no. It's really that I went for the overall arc of the piece. So in that sense, the answer is yes, because different characters are ahead with the knowledge than others about what's happening. So when we went to the stabbing, and then we cut back to Margaery, she doesn't know yet what's happening obviously. They're still all waiting on an answer. We knew the music had to calm down again and come back into a holding pattern. I had to pull it back, and that's when we went back into the piano again where we were in the beginning, but with a little bit more going on, because now we're into the piece and we overall have to get to the end and keep climbing. I didn't want to go and reset entirely. But maybe that's what describes the piece best. We have these moments of crescendo, then it falls back a little bit, goes into a holding pattern, and climbs again. But overall, the piece is steadily climbing.

Can you talk through the recording of the piece?

It was definitely assembled. The boys I recorded completely separate. The strings I recorded all together. Even the solo instruments, I recorded them separately — the solo violins and solo cellists were recorded separately. The piano, I played. And the organ as well.

So not only were you bringing in a new instrument with the piano, you were the one physically bringing it to the show as well.

I love performing on my own scores. I do it quite a lot. Back in my teenage days and in college and everything, I did a lot of playing. If I had time, I would play a lot more. I don't get the opportunity to record as much anymore. If there's an instrument I can perform myself, I'll do it myself. I really enjoyed it. And the organ is actually the instrument I started out on as a kid, when I was 4 years old. I was so young I couldn't even reach the pedals with my feet. (Laughs.) I played it standing up. From there, I went and learned the piano. But it started with the organ. That's what I knew how to play.

Did composing this season's score feel particularly distinct from previous seasons?

Definitely. I think the sheer amount of music this season was different. Historically, the early episodes tend to be a little lighter with music. Toward nine and 10 is where the battles pick up and we get into the finales. We've always had big cues there. But this season, we had these big music moments from very early on, because the story is at such a high level. It's expanded so much and there's so much at stake at this point that we had these big moments. All of these Daenerys moments, for instance, like when she burns down the hut and flies in with the dragon, and the Hodor moment in episode five. All of those could have been finale pieces. They were all big set pieces, and musically, I had opportunities to go with big orchestra and choirs. We opened it up with the score, which was so much fun.

How happy are you with the reaction to the piece?

It's been great. What I love is that Game of Thrones is always up for surprises. Every season you go, "Who's going to get killed off? What are they going to do next?" I have to do the same with the music. In the past, we've had different bands perform, like "Rains of Castamere." And it would become, "Which band is it going to be this season?" But it seems that with Game of Thrones, whenever you think you've fallen into a pattern, it takes you somewhere else. I feel we did the same with the music. People maybe thought, "What's the band this season?" Well, we don't have a band, but here's a new piece of music with new instrumentation that we've never had before. It took people by surprise, and I love that.

Are you prepared for the "Light of the Seven" heavy metal cover?

I hadn't even thought about that! (Laughs.) But it would actually make for a great one. I can hear it in my head. I can totally hear that right now.

Watch the explosive scene, and hear the end of "Light of the Seven," in the video below:

Follow THR's Game of Thrones coverage for more interviews, news and analysis.