Buffy the Vampire Slayer Season 2 Episode 4 : Inca Mummy Girl

While on a visit to the local museum one of the students accidentally breaks an ancient seal buried with an Inca Mummy. Without the seal to hold her, the mummy rises and must consume the life force of the living in order to stay alive. When she consumes the identity of Ampada, an exchange student, Buffy have to stop her from seducing Xander into her death list.