Generation Y’s version of Rush, these New York prog-rockers have used their yowling albums to chronicle the Amory Wars saga, an epic sci-fi fantasia involving a 78-planet solar system called Heaven’s Fence and . . . oh, never mind. Storywise, Album Five is as labyrinthine as ever: A deluxe version comes with a 352-page novel co-written by frontman Claudio Sanchez. Musically, though, it’s the same old mix of impressive musicianship and arena-size agita. Coheed sometimes write a fetching tune — see the tender ballad “Far” — but Rainbow feels both silly and retrograde.