“The five minutes of “As Fathomed By Beggars and Victims,” the first cut from Obsian, the second album by Brooklyn art-metal trio Castevet, seem always to be hanging on by a string: Nicholas McMaster's bassline slides in and out of the groove that's shaped by frantic acoustic guitar runs and restless drumming, as if threatening to waylay the song before it really starts. That feeling of unrest not ”