Black Mountain are a little bit Hobbit and a little bit Orc. The Vancouver quintet play flower-brained folk and Satan-friendly hard rock to evoke that moment when the hippie dream got creepy. Their third disc is their heaviest and most concise. “Play those dead-wish chords,” singer-guitarist Stephen McBean and singer Amber Webber entreat on the deeply purple doom boogie “Old Fangs.” And, boy, do they. Wave after wave of British metal crashes against misty mountains of luded-out acoustic mellowness. But it isn’t just a stoner put-on. “The Hair Song” sweetly celebrates getting back to the land and “children” playing the blues; it’s a vision of incense and innocence that’s impossible to fake this well.