Obito used the expelling force of his Kamui to create a giant vortex with his Katon - so it was a Fire Release + Doujutsu technique. "Bakufuu" = "Blast" ; "Ranbu" = "Wild Dance" --- since adjectives, nouns and even adverbs are positioned differently than in English, this roughly translates into "Fire Release: Wild Dance Blast". Like TheDreamShark stated, it could be translated into a more flowing statement like "Chaotic Dance of Exploding Winds".