In 1968, New Orleans keyboardist Mac Rebennack reinvented himself as a slightly sinister swamp spiritualist known as Dr. John, the frog-voiced Night Tripper. Rebennack and his crew's strange brew mixed San Francisco psychedelia with New Orleans R&B, which sounds especially effective in "Gris-Gris Gumbo Ya Ya" and "I Walk on Guilded Splinters"—heavily percussive, chant-driven tracks suggesting something ominous rising from the swamp. "Mama Roux," meanwhile, whips up its own Afro-Cuban magic.