By the fourth entry in the series, the Nightmare formula was largely solidified. There’s a house on an unassuming street in which unspeakable things have happened. There’s a cohort of teenagers being pursued by a supernatural murderer who inhabits their dreams. There’s Robert Englund in a red and green sweater, wearing razors on his hands and telling one-liners. There are creepy kids singing a song on the soundtrack. But you don’t come to a movie with a 4 in the title for novelty or experiment — you come for the gross-out effects, the tongue-in-cheek cultural parody and the potent mix of humor and horror. There’s plenty of all of that in The Dream Master.