Slayer
(Book)

"From the world of Buffy the Vampire Slayer" -- jacket.

Nina and her twin sister, Artemis, grew up at the Watcher's Academy, where teens are trained as guides for Slayers-- girls gifted with supernatural strength to fight the forces of darkness. While their mother is a prominent member of the Watcher's Council, Nina has never embraced the violent Watcher lifestyle. Instead she follows her instincts to heal, carving out a place for herself as the school medic. Until her life changes-- and now Nina is not only the newest Chosen One-- she's the last Slayer, ever. Period. She's honing her skills on a monster fighting ring, a demon who eats happiness, a shadowy figure that keeps popping up in Nina's dreams... and then the bodies start turning up.... -- adapted from jacket