The riffs are heavy, as is the female presence. Of metal’s many strains, perhaps none has seen such a welcome influx of woman-fronted bands as doom has in recent years: Demon Lung, Windhand, Lucifer, Witch Mountain, Jex Thoth, Blood Ceremony, and Ruby the Hatchet being but a few of the standouts. Add Castle to this lady-centric list. The California power trio distinguish themselves from their more haunting, ethereal-sounding peers with a bluesy, classic-rock-informed bombast. Singer-bassist Elizabeth Blackwell’s gut-bucket vocals don’t float through the band’s tunes like pretty poltergeists; instead, they power them. She’s like Heart’s Nancy Wilson smothered in leather and denim, her band’s tunes colored in the deepest shade of purple.