Board Thread:Theories and Speculation/@comment-1512913-20161115123051/@comment-1512913-20161115134213

Well, Explosion is only assumed here to be Earth + Lightning, because during Sasuke's battle against Deidara, Sasuke identified that Deidara used an Earth Release hand seal or something like that and people took it for granted and added Lightning because it was the only unused nature not yet combined with Earth. For Magnet, the only reason why it's Wind + Earth, is because 4th databook Jin no Sho, which is full of errors, lists Rasa, the 4th Kazekage's natures as Wind, Earth, Water, Yin. There's is no more evidence or proof beyond that.