'Mortal Instruments' Has Jamie Campbell Bower 'Kicking Ass'

'He brings this wit and charm that only Jamie can bring,' co-star Lily Collins tells MTV News, also marveling at his stunt prowess.

He's played a dark wizard and a villainous vamp, but actor Jamie Campbell Bower is tackling his most physically demanding role yet in the upcoming "The Mortal Instruments: City of Bones" as demon-destroying Shadowhunter Jace Wayland.

Based upon the urban fantasy series by Cassandra Clare, "City of Bones" stars Lily Collins as a Brooklyn teen who discovers she's a descendant of an ancient line of half-human, half-angel warriors tasked with protecting Earth from dark forces. Campbell Bower plays her love interest in the film, and the actress had plenty of accolades for her co-star when MTV News caught up with her at the Toronto International Film Festival recently, where she was supporting another film, "Writers."

"When he walked into the room for the audition — I remember telling you this actually, a while ago — that he walked on and that was it. That was Jace. He nailed it," Collins recalled. "He didn't have to try. He's that perfect mixture between being this, like, mysterious Jace and also very endearing and funny, and he brings this wit and charm that only Jamie can bring. You just burst out laughing because he's so deadpan when he delivers things."

But a sense of humor isn't all Campbell Bower is bringing to the role. The actor has been hard at work training for a number of wham-bam action sequences. "Like I said, he's doing all of his stunts, so he's kicking ass doing flips," Collins said. "And it's really impressive and the same with all the other castmembers. We are in it, and we are really being dedicated to the book and bringing a new flair to it."

Though the script, penned by "Pretty Little Liars" executive producer I. Marlene King, isn't a word-for-word adaptation of Clare's source material, Collins assured that anxious fans have nothing to worry about.

"I think fans are going to be very, very happy," she said of the screenplay. "Cassandra Clare wrote amazing stories. She came here, and we've talked to her and seen her, and she's very happy. You wouldn't want to take away from the beauty of what she's written. Of course, you know films, you take a little bit of license in certain parts. I feel like it's only enhancing the story. It's making it a little edgier. It's making it something that I think fans of the book are going to love, but people who don't know what the story is about are going to love it as well. So it's not just an adaptation of a book; it's a movie that can stand on its own. I'm really proud of it so far."

With production underway in Toronto, we couldn't help but wonder if Campbell Bower had made good on his threat to get a "Mortal Instruments"-themed tattoo to commemorate the project.

"Not yet, but it's been talked about!" Collins said. "With Jamie, you never know, right?"

When Josh Horowitz asked if the entire cast would pull a "Lord of the Rings" and get matching ink, Collins didn't necessarily poo poo the idea. "Maybe we'll all get something," she said with a grin.

"The Mortal Instruments: City of Bones," also starring Jonathan Rhys Meyers, Lena Headey and Kevin Zegers, will hit theaters in August 2013.

Check out everything we've got on "The Mortal Instruments: City of Bones."