With razor-sharp verbiage and wildly imaginative beats, this is a classic combination of two hip-hop super-villains in their prime. Metal-faced rap linguist MF Doom spins crime narratives over bopping bass strums on “Meat Grinder,” and cheerfully harmonizes out of tune over orchestral jazz on “Rainbows.” Dusty fingered producer Madlib loops wonders out of obscure vinyl records, whether it’s the melodic drone of “Accordion” or the skipping guitars and koan-like tone of “Shadows of Tomorrow.”