Beginning with his classic debut, Illmatic (1994), Nas stood tall for years as one of New York City's leading rap voices, outspokenly expressing a righteous, self-empowered swagger that endeared him to critics and hip-hop purists. Whether proclaiming himself "Nasty Nas" or "Nas Escobar" or "Nastradamus" or "God's Son," the self-appointed King of New York battled numerous adversaries for his position atop the epicenter of East Coast rap, none more challenging than Jay-Z, who vied with Nas for the vacated throne left in the wake of the Notorious B.I.G.'s 1997 assassination. Such...