Long before the cameras started rolling on Thor: Ragnarok, the concept artists at Marvel Studios got together to do what they’ve always done: something Walt Disney called “plussing.” It’s basically a series of brainstorming sessions in which scores of possible designs are drawn up. “The thinking behind it is there isn’t a right answer,” says Jake Morrison, a Marvel vet who’s supervised visual effects on all three Thor films. “And any concept that you can [make] better, you should.”

During the plussing process, even a character like Chris Hemsworth’s Thor, who thundered about for four movies prior to Ragnarok, gets design adjustments. But when it comes to a new character like Cate Blanchett’s Hela—the Goddess of Death, and the first female villain of this cinematic universe—the number of alternate designs literally climbs into the hundreds.

“There’s never a moment where everybody is standing there, patting themselves on the back, and going like, ‘Wow, we made something incredible!’” Morrison explains. “Everybody is always going like, ‘How can we improve it? What’s a better version of this?’ So what that means is the sky’s the limit—especially when you have a character [with] a magical component.”

The social-media feeds of Marvel concept artists Andy Park and Ryan Meinerding are littered with character designs that didn’t make it to the big screen. (Did you know that Mantis in Guardians of the Galaxy Vol. 2 used to be yellow and more bug-like? Or that Vision in Avengers: Age of Ultron was once Marvel’s literal golden boy?) Soon enough, they’ll probably show off nixed versions of Hela, too—once Marvel gives them the O.K. to release these alternate designs.

Morrison, who typically comes aboard a Marvel film as early as pre-production, describes the process of designing Hela as “a crazy free-for-all.” Why? Blame (or credit) the script: “She has to get stabbed in the suit, and then the suit heals around it. There’s a moment where her cape absorbs bullets . . . there were moments where we actually had the antlers”—their affectionate nickname for Hela’s battle headgear—“turn into face-mask shields and stuff like that, almost like samurai-style outfits.”

The team was initially inspired by the comic-book imagery of Jack Kirby—what Morrison describes as “the Kirby crackle” of lightning that illuminates a darkened Asgardian sky. But with Taika Waititi aboard Ragnarok, the director wanted to take the film in another direction: more Flash Gordon 2 than Thor 3. “Taika actually took all us heads of the departments into a screening room, and sat us all down, and had us watch Flash Gordon at one point,” Morrison says. Luckily, Kirby also dabbled in sci-fi stories like Amazing Adventures and World of Fantasy—so the team turned to those for inspiration as well.

Hela also comes with some baggage in the form of her very own dire wolf. In Norse mythology, the end-of-days that is Ragnarok involves a giant wolf named Fenrir devouring the sun. That doesn’t happen in Marvel’s interpretation of the concept, but our villain does get Fenris, a 35-foot-tall black beast with glowing green eyes.

“Having just done Ant-Man for two years, I can tell you that scale is one of the biggest challenges in any sort of storytelling,” Morrison says. It’s a matter of perspective: a movie can’t just blow up a standard-sized wolf because it would look fake, largely due to the amount of hair on a normal dog.

“So what happens is you have to maintain this plausible deniability where you go, ‘Well, actually . . . Fenris’s hair is maybe a little thicker than a normal dog,’” he says. “And then all of a sudden you end up with—and I’m just gonna pull numbers out of thin air—if you end up with, like, 10 million hairs on a typical dog, all of sudden you’re gonna have like 200 million hairs on this dog, because you can’t just make the hairs bigger.”

Courtesy of Andy Park/Marvel Studios.

The first image to be released from Ragnarok was concept art of Hela, antlers extended and standing with her back to the viewer as she prepares to unleash hell on the soldiers of Asgard. This became a keyframe for Marvel, a benchmark of sorts the production team used as a guide for the rest of the sequence.

“You start with that artwork, and then literally we start to do choreography with our stunt department,” Morrison says. The biggest question they had to answer: how does Hela fight? “Is it more of a wushu style?” Morrison asked himself. “Does she spin? We know she’s got to throw out these blades one after another, so maybe it’s more like wushu—but instead of holding the knives, you’re throwing the knives.” These questions help form the basis for the character’s own unique “language” of movement, he says, which the stunt team can feed off of.

For this film, Marvel developed what Morrison calls “the smallest, active motion-capture markers that have been made yet.” Instead of wearing the standard gray motion-capture suit, the crew placed those markers all around Blanchett’s Hela costume. The Oscar winner and her stunt double, Zoë Bell, were then filmed performing the majority of the sequences, and their movements influenced the C.G.I. wizardry that would come in post-production.

Her invasion of Asgard was a particularly tricky sequence that went through three fundamental reconstructions. “At one point, it was one continuous shot. I kid you not,” Morrison recalls. “We went a long way down the path with that . . . and actually it was a revolving camera as she tracked through and killed everybody.” In the end, though, they completely re-edited the sequence because they found it more “percussive” broken up.

Another challenge? The scene in which the wolf Fenris fights a hero in a waterfall, which was particularly difficult for the V.F.X. artists: not only did they have to animate millions of hair strands, but each needed to look convincingly damp. No wonder Morrison called the scene “absolutely cracked.” In the end, all their work comes back to the idea of plussing: “There’s no sacred cow, that’s for sure,” he says.

Thor: Ragnarok is now playing in theaters.

Thor: Ragnarok: How Marvel Conjured a Hela-Awesome New Villain