Shouldn't Elemental Lux have 1 more form?

We know you start in Light form then pick Earth Wind Fire or Water (the left 4 in the original teaser)

From there you pick a second element that combines with the first to create your third form of the game.

So I'm pretty sure

Fire + Wind = Lightning Water + Wind = Ice Fire + Earth = Lava

But that leaves the purple and dark forms and it leaves the following combos

Fire + Water = ?? Water + Earth = ?? Earth + Wind = ??

Which you'd need 3 forms to cover not just 2. Ergo unless 2 of the above combos create the same form, or one of them turns you back into light form, there should be one more.