Board Thread:Theories and Speculation/@comment-25283946-20150203145352/@comment-3279282-20150203194518

You need a Kekkei Genkai to combine chakra, though. So even if Blaze Release was Fire + Yin, it would still be a Kekkei Genkai. Which it is, according to the databook, but we don't know if it is because of the Mangekyo Sharingan involved or not.