After single-handedly redefining “warped” as the mind and mouth behind the Bronx-based Ultramagnetic MC’s, “Kool” Keith Thornton — aka Rhythm X, aka Dr. Octagon, aka Dr. Dooom, aka Mr. Gerbik — headed for the outer reaches of the stratosphere with a variety of solo projects. A onetime psychiatric patient at Bellevue, Keith’s lyrical thematics remained as free-flowing here as they ever were with the N.Y.C. trio, connecting up complex meters with fierce, layers-deep metaphors and veiled criticisms of those who “water down the sound that comes from the ghetto.” In the midst of his ever evolving career. Keith is, of course, one of the pivotal figures in the history of hip-hop, and has been one of the genre’s most singular writers and original voices. The Bronx native was a founding member of Ultramagnetic MCs, whose debut album, 1988’s Critical Beatdown, served as a blueprint for both internationally famous acts like Public Enemy and for the entire future of underground rap. But Keith’s solo work, which began in earnest in the mid-’90s with Dr. Octagonecologyst (released under a pseudonym, naturally) is even stranger, more experimental, more brilliant. He will enjamb seemingly unrelated ideas and images against one another with a poet’s love for language and a pornographer’s knack for camp. Subsequent records like 1997’s Sex Style, ‘99’s Black Elvis/Lost In Space, and 2000’s Matthew were hailed as instant classics; Keith has spent the last several years crafting expertly written records that are rewardingly bizarre, unlike anything else on the rap landscape.