Mastodon have taken some hits from the faithful recently, with detractors claiming the Georgia metal band have blunted their edges since signing to Warner Brothers. Though 2009′s Crack the Skye felt like a triumph, it’s follow-up, 2011′s The Hunter felt a little too direct. The opening moments of “High Road,” from the forthcoming Once More ‘Round the Sun handily remedies that. A batch of jackhammer riffing, it clobbers ruthlessly. Though the song eventually settles into gleaming, high-altitude chorus, there’s a snarl and dissonance that makes it feel dark and threatening. It’s a potent, bracing opening volley.