The image on the cover of Mogwai’s seventh LP — traffic against a dusky morass of urban sprawl — evokes the music contained inside. Ethereal guitar and synth melodies streak like headlights in the fog. This contrast drives the album, as Mogwai marries strikingly subtle compositions to some of the most oceanic guitar layering since Loveless. With Mogwai, as usual, emphasizing instrumentals, Hardcore’s density is intimidating at times, but repeat listens pay remarkable dividends — snaky, Fripp-like leads spring out of “Death Rays” like flowers blooming in time-lapse, while “Rano Pano” uses pointillistic guitars to approximate a spectral echo of Pixies without vocals. Elsewhere, “White Noise” and “Letters to the Metro” are surprisingly warm and accessible, even with the latter’s glacial pace, and the album’s lumbering, Slint-like closer, “You’re Lionel Richie,” is every bit as great as its title.