Overkill had assimilated multiple styles of metal into its sound over the years, but thrash was its native territory. The band returns to that land at the start of its 14th studio album, Immortalis. Bolstered by the guitars of Dave Linsk and Derek Tailer and the lightning-fast double-bass drumming of new recruit Ron Lipnicki, “Devils in the Mist,” “What It Takes," and “Skull and Bones” form a master class in thrash dynamics. These tunes have it all: abrupt rhythms, quick guitar breaks, cathartic solos. Other groups do that too, but Overkill simply does it with more aggression and creativity than its rivals. Even when the band delves into the thicker, thrusting grooves of “Hellish Pride,” “Head On," and “Chalie Get Your Gun,” there's something unique about this group’s singleminded devotion to pure ferocity. And while many metal bands eventually devolve into parody, with unintelligible vocals and muddied rhythms, Overkill always comes off like a rock band in the classic mode, especially on the brilliant “Walk Through Fire.”