Though heavy metal’s interest in Satanism and witchcraft dates back to the ’70s, Mercyful Fate turn them into full-blown obsessions on their game-changing debut. No ghastly topic is off-limits—necrophilia and ritualistic murder included. The utterly singular King Diamond leads the procession: His multi-octave range allows him to shape-shift from shrill banshee to growling demon at the drop of a hat. Likewise, the music swings abruptly between neoclassical opulence (“Into the Coven”) and quick-fire assaults powered by drummer Kim Ruzz’s NWOBHM-style blitz (“Black Funeral”).