@Riot About Yuumi.....
When she is attached to an invisible champion, will she go invisible as well?
Also, As much fun as I would have to play her and be just like "ok, heres a good chunk of attack for each of us." I feel like the conversion ratio should be WAAAAY low. Maybe 10% or 15%.... but nothing much more than that. Non scaling. Otherwise, you might finally have an ADC hit quadruple digits in attack..... and that is scary to think about.
Yes, it can give more stats than Janna's shield, but even 100 extra stats is SCARY to think about on any champion that has any kind of high ratio.