Shapeshifting champion idea

So on my way to work I was thinking what if League had a true shapeshifter as a champion?

I know we have Gnar, Nidalee, and Elise who are shapeshifters but I was thinking of something more difficult.

The shapeshifting power would allow you to become essentially any champion in league.

I know that sounds disgustingly OP but before we call the idea stupid I’ll explain the mechanics first.

The idea I had for this to be implemented would be for a champion to have a shapeshifting ability tied to their ultimate.

Your ultimate would be some sort of execute/mark that you would place on a low hp or squishy enemy if you manage to successfully kill your target you consume them and become them.

Now while your ultimate is on cool down you now have the ability to switch back and forth from yourself to the person you killed. While switched you gain their appearance, animations, abilities, and base stats. You don’t gain their items/runes/passive stacks. Not sure how they should interact with other shapeshifters but I think taking on the appearance of their base form or the form you killed them in should work (I.e. you kill Nidalee in Cougar form you now have Cougar form).

I haven’t yet worked out the particulars but I imagine this Champion would work effectively as a true hybrid who should be able to work with any items.

Right now I can’t think of an appearance for this champion other than a Goo Girl/The Thing/Blob or something of that nature but that maybe encroaching on to Zac’s theme.