"Adaptive" Champion?

I have to say, I really like what Riot is doing with the upcoming Runes. If you don't know, a bunch of runes are being made that grant "adaptive" stat bonuses, giving AP or AD based on what you already have more of from items and runes and etc. So if you're building AP, these adaptive runes give you more AP. If you're building mainly AD, they give you guessed it, more AD. I really like these because they're quite flexible not just based on champion but also on build, and it actually gave me an idea; what if you took this concept to its logical conclusion and made a champion focused on it?

So that's where this idea came from. "This idea" being a champion whose abilities and performance change on a functional level based on build, similar to Kayn's transformation mechanic but distinctly different. The idea lends itself nicely to a "Magus" or "Spellsword" thematic that League is missing, and would honestly be really cool to see.

Sure it's a vague idea, but what do you guys think? I'd really like to see Riot explore this idea, personally.