Transformation Champion Idea

Okay, when I say this, you're thinking of or . Yes... but no.

I mean a transformation like Nidalee's, but has a time limit just like those listed above. A full new moveset, with different base stats and passive; for 7 - 10 seconds.

Ideally, this would be a champion who goes from AD Fighter to AP Artillery. If you have any ideas on this, please speak up in the comments.