An Idea for a New Style of Dual Form Champions

My idea is kind of a combination of Karma and reactivated abilities (ex Vel'Koz Q). I came up with this as a champion that controls both water and ice. Their ultimate allows them to swap between the water and ice form of their abilities, and its on an exceptionally short cd (maybe 1-2 seconds). Just swapping forms would cost 0 mana. However, swapping forms while an ability is in use would cost mana and give the ability some sort of cool new effect ONLY accessible in this mid use swap. Think of it kind of how you can throw out a q as Annie and proc the stun mid flight with e.

So lets say your q throws out a half circle of water in a targeted direction. Using your ultimate while the water is traveling would turn that half circle of water into ice and deal increased damage with a minor knock back. Now that you are in ice form, your q would give you a shield of ice. When you use ultimate before the shield expires, it melts and uses the water to form a maelstrom around you. I don't think these abilities pair well for being each being on q, but its just to show how different you can make 12 abilities (13 if you count ult) on only 4 buttons.

Its also worth noting that this ability would not be restricted to swapping one ability at a time. Any number of abilities currently in use would be all swapped by your ultimate.

Just an idea for a champion with the most flexible (or complex depending on how you look at it) combos without going full Invoker.