Board Thread:Consensus Track/@comment-3279282-20160412110535/@comment-1512913-20160413133135

Well, let's take a look at our advanced natures across the media, in canon relevant order.
 * Ice = Wind + Water
 * Wood = Earth + Water
 * Lava = Fire + Earth
 * Storm = Lightning + Water
 * Boil = Fire + Water
 * Explosion = Lightning + Earth
 * Scorch = Fire + Wind
 * Magnet = Wind + Earth
 * Dust = Fire + Wind + Earth
 * Crystal = ??? (SPECULATION) possibly kekkei tōta = Wind + Earth + Water (being very similar to Ice, so kinda like Ice + Earth)
 * Steel Release = ??? = Fire + Earth + Water?, Fire + Wind + Earth?, Fire + Lightning + Earth? but it's a genkai, hmph...)
 * Typhoon = Wind + Lightning?

If so, the only left unused dual combination is Fire + Lightning.