Buffy is known for it's traditional Halloween episodes. Given the nature of the show, it makes sense and it's a cool characteristic that follows in the lines of The Simpsons (Tree house of Horror) and Friends (Thanksgiving).
Unfortunately there's nothing here that's scary, fun, or really, very interesting. Hearkening back to the classic episode where costumes turned trick-or-treaters into literal manifestations, here, it is a fraternity haunted house that becomes a REAL real of terror! This is due to careless use of an old mystic symbol, and the gang gets split up inside, everyone facing their worst fears. Too bad the material written here wasn't stronger, because the potential was great.
ONLY GOOD MOMENT: Anya arriving in her bunny suit. Funny (and oddly, hot..)