I was thinking about supports that want to focus on healing/shielding and buffing more than damage. The only real healing-related keystone is Aery and aery is kind of weak because it's made for damage and protection. Guardian is for tanks so I'm gonna ignore that.
Is there any possibility we could get something like "Your next heal/shield on an ally below 30% is aoe and allies within 250 units are granted 20-36% of the heal and 14-40 movespeed".
I think it's fair because chances are your heal will bring them past 30%, and 15% of the heal is not much. That may only be a 50 hp heal full build. For somebody like sona it still shouldn't be super broken compared to her current options. I don't believe it'll even be noticeable in laning phase because that'll be 7 hp heal in laning phase on sona.
Currently, if I want to play super-healer Nami I gotta go aery for the tiniest little buff to allies. I'm pretty sure people only take Aery for the damage anyway. So I'd rather take something like electrocute since aery isn't exactly the most bloodthirsty option for me. You could also just rework aery since completely random champions are taking it. I've seen Draven, Olaf, Ezreal, Darius etc... take it, they shouldn't even be able to see this an an option.