Over more than a decade and a half, listeners have learned to expect the unexpected from Ulver, who started out as a Norwegian heavy metal band but have turned far more experimental.

War of the Roses begins sounding like a fairly conventional rock album, in which the mainstream track "February MMX" boasts socially conscious lyrics ("genocide is suicide"), and "September IV" also suggests mainstream rock.

But more of the album is given over to selections like "Norwegian Gothic" and especially the nearly 15-minute closer, "Stone Angels," with slow, ambient tracks featuring sound effects and poetic, spoken word vocals.

The closest antecedent, notably on "England" and "Island," with their slow, ponderous tempos and calm vocals, is Pink Floyd, making Ulver as of 2011 something of a neo-progressive rock band with a bit of Radiohead thrown in.