Board Thread:Theories and Speculation/@comment-27082825-20150116155842/@comment-26023629-20150122162205

Yeah, that's closer to my idea. Dust isn't combining lava and magnet so much as it is combining the basic natures that make up those advanced natures. Under this theory, Mei has two advanced nature kekkei genkai and not a kekkei tota because the genes didn't blend. I imagine achieving the creation of a kekkei tota would have quite a bit of trial and error involved, and given the negative disposition the Land of Water had towards kekkei genkai users, it's likely they wouldn't have made an effort to blend them (or even considered that idea). Or, perhaps the neutral element theory holds water and that's why she didn't form a kekkei tota.