Metal’s sonic palette is in no danger of stagnating. The artists included here span a wide musical gamut—some couldn’t be further from each other while still retaining some loose affiliation with metal—but they’re all leaning hard against the genre’s boundaries with varying degrees of experimentation. Avant-garde and forward-thinking work seeps from places around the world, in the form of dissonant power dirges (Japan’s Boris), cinematic death-doom (Switzerland’s Triptykon), sprawling electro-inflected grooves (Italy’s Ufomammut) and frenetic space sludge (Norway’s Shining). Not to be outdone, American artists like Sunn O))) and Pelican eschew vocals and strip metal down to its bare essentials, offering up rumbling sub-bass drones and gleaming instrumental triumphs. And bigger names like Opeth and the Dillinger Escape Plan offer musical excursions informed by pastoral '70s prog and shimmering R&B, respectively.