Beginning as a fairly straightforward second-wave black metal band and drawing comparisons with all the usual suspects — Darkthrone, Burzum, et al. — Nachtmystium has since become one of the most integral purveyors of USBM. Interestingly, the Chicago band achieved its creds by sometimes not being very black metal at all. The sweltering psychedelia on 2006's Instinct: Decay broke the band out of the esoteric metal underground, garnering praise from the indie elite and metalheads alike. The band's latest, Assassins: Black Meddle Part I, carries the what-if-Pink-Floyd-were-a-metal-band approach, going so far as to reference Floyd in its title while venturing further into thick layers of atmosphere. While the album is likely to upset black metal purists, it goes a long way toward expanding the genre's boundaries and cementing the reputation of an increasingly important American metal band.