She plays Katarin, the main villainess of the movie.
Sebastian, Vladimir, and Katarin are three members of the Brimstone Society, who fight vampires. She betrays Bloodrayne and her companions, giving their positions to the ennemy. Later in the movie, Bloodrayne finds her, and their fight ends up with Katarin being killed.
Katarin wears a nice grey cape, attached to both shoulders, which she uses in a fight to blind her oponent. She also uses it to wipe her dagger after a kill.