Rapper Slug has built his career on brutally earnest narratives and savage, sharp-toothed humor—see God Loves Ugly and When Life Gives You Lemons, You Paint That Shit Gold. Now firmly toeing middle age, Atmosphere’s latest release, The Family Sign, is a heavier offering to fans, one with a slower tempo, themes of spousal abuse and fatherhood, and a noticeable lack of levity. But while Atmosphere’s sound may still be evolving, after nearly two decades of touring, Slug’s stage presence has been honed to the hypnotic force of a freshly sharpened pitchfork. (Showbox at the Market, 1426 First Ave, www.showboxonline.com, 8 pm, $25 adv/$30 DOS, all ages)