Metallica’s debut album proved a shocking and audacious opening battle cry for a new generation of metalheads who were crawling around the metal underground looking for a leader. Released in 1983, Kill ‘Em All combined the primordial, rudimentary riffage of Black Sabbath with the intricate, melodic overtures of Iron Maiden played at the speed of Motorhead and hardcore punk. This new ‘thrash’ became the schematic for hundreds (thousands?) of bands that would follow, eschewing commercial heavy metal’s penchant for big hair, spandex and pop hooks and replacing it with full-on aggression. Later releases would expand on their approach and reach greater compositional complexity, but for sheer raw power tracks such as “Hit the Lights,””Jump in the Fire,” the appropriately named “Whiplash,” and “Seek and Destroy” are unrelenting. Singer James Hetfield’s histrionic growl still elicits strong melodies as it keeps time with his carpal-tunnel rhythm guitar playing. Drummer Lars Ulrich’s boundless energy never flails. And underneath the maniacal charge, one can hear the beginnings of the lyrical guitar lines that guitarist Kirk Hammett and bassist Cliff Burton would bring forth with greater emphasis on later releases. A basic metal primer.