On Fornever, the fourth collaborative album by MURS and producer 9th Wonder, the duo is smart enough not to tinker with a winning formula. “Cigarettes & Liquor,” “The Lick,” and “Live From Roscoe’s” find MURS playing hood sociologist as he explores, respectively, the irresistible pull of instruments of self-destruction like cancer sticks and malt-liquor bottles, and the self-contained universe of the corner store and waffle house. MURS is part of a vocal minority of rappers who rhyme about women within the complicated, sometimes frustrating context of relationships, rather than viewing them as mere conquests. On “Vikki Veil,” he pays for nights of carnal bliss with boundless insecurity after falling in love with a porn star, while on “Let Me Talk,” he gets into the kind of PMS-fueled domestic squabble that generally precedes a long stint of sleeping on the couch. But the pimpadelic Suga Free scores the album’s meanest, funniest line when he observes of a hood rat, “Her son’s retarded, right? I can’t lie / One day a butterfly landed on his nose and brought a tear to my eye.” MURS pointlessly remakes Common’s seminal hip-hop allegory on “I Used To Love Her (Again),” adding nothing but a line about Auto-Tune and making it rain. On that unnecessary cover, he simply recycles hip-hop’s past; elsewhere he smartly, subversively reinvents his beloved genre in his own prickly, iconoclastic image.