Godsmack are a three-headed beast, capable of unleashing psychedelic post-grunge, back-alley hard rock and intensely rhythmic nu-metal. The Boston outfit hit the ground running with the 1999 smash “Voodoo”, in which Middle Eastern-infused percussion and bass-anchored harmonies dance together like charmed snakes. 2002's “I Stand Alone” couldn't have been more different—all grinding riffs and lumbering drums. Sully Erna matches the music's versatility with vocals that bounce between guttural screams and otherworldly groans.