Well the thing is AST has one button for 6 different actions and the action is RNG, you'd have to create a system where 3 elements cycle to their opposite element under certain conditions or something in that area. And then you have the underlying issue that plagued SMN before 4.0, only using whatever summon maxes your throughput, in that instance Garuda. You'd have to give incentive to switch elements, perhaps have some base spells that change with your elemental attunement or put them on a timer, kind of like how Bard rotates through their songs.