Season 3 Episode 12
Episode aired january 19, 1999
as her birthday approaches, buffy loses her slayer powers and must do battle with a vampire who is not only extremely powerful but also quite mad.
on the original idea presented by writer david fury, the drug giles gives buffy would make her hallucinate that her mother and friends had turned into vampires, but with the wish (1998) so close in time, joss whedon and david greenwalt changed the content of the council test.