Hip hop beefs are things of legend, fueled by media frenzy, record sales and egos. Tupac and Biggie. Nas and Jay-Z. Kool Moe Dee and LL Cool Wack. All of these notorious B.E.E.F.s are about to be eclipsed, though, by the rivalry simmering between Professor Elemental and Mr. B the Gentleman Rhymer, a rivalry that spans an empire.