In the Southern gothic world imagined by authors Kami Garcia and Margaret Stohl in their best-selling "Beautiful Creatures" novel, light and dark wage a war for the soul of young caster Lena Duchannes, whose destiny will ultimately be decided on her 16th birthday. Each side claims strong allies, but none is quite so beautiful (and bad) as Lena's cousin Ridley, portrayed in the upcoming film adaptation by "Shameless" actress Emmy Rossum. When MTV News visited the New Orleans-based set to talk all things magical with the cast, Rossum gave us our first look at Ravenwood Manor and offered plenty of insight into the deliciously dark dame she portrays.

"I play Ridley Duchannes, and she is a fine Southern young lady, and she is a dark caster," Rossum explained. A caster is someone who can use magic — what we would call a witch. "She was claimed for the dark when she was 16 and since then has been basically up to no good, which is a lot of fun to play. Basically, my role in the film is to come back and ensure that Lena Duchannes, played by Alice Englert, her cousin, turns dark when she turns 16."

Like any caster, Ridley has her own special power. If you're familiar with the Sirens of Greek mythology, then you have some early insight into the kind of influence Ridley wields.

"Ridley's main power is the ability to manipulate people, especially men, and to use her charms to get what she wants, whatever that is," Rossum said.

On this particular day trip to the fictional Gatlin — where Lena and her mortal beau Ethan (played by Alden Ehrenreich) must face a slew of supernatural hurdles in order to be together — the cast was filming a pivotal moment in which Ridley returns unannounced to the family home after being banished.

"The scene we are filming today is the most important scene for Ridley," Rossum said. "It's kind of her turning point, her big moment where she makes stuff hit the fan, and it's really fun to kind of manipulate and play with the dynamic and undercurrents of the character. Is she all evil? Does she have goodness inside? When is she really being herself and when is she really playing people? It's really fun for me to play."

In keeping with what we saw during our previous visit to set, today's scene also featured real special effects instead of computer-based enhancements.

"Everything on this specific set actually moves and actually does the things it says in the script, which in most films would be completely CG," Rossum explained. "This is all actually happening, so as actors, when we walked on to the stage and realized the chandelier does actually move, the chairs did actually spin, the table did actually spin, there was actually going to a be a hurricane actually happening while we were shooting, it was all very exciting."

"Beautiful Creatures" opens February 13, 2013.

Which scene are you most looking forward in the "Beautiful Creatures" movie? Describe it in the comments!