Unused Mechanics?

As I sat there the other day pondering on the potential for a new support champion, one that operated differently from the current ones, I wondered to myself about what type of mechanics aren't even in use currently.

For example if we wanted to make some sort of Symbiote/Parasite type champion then there are two different approaches I could see them doing: One of those approaches would be a "Tether" system where you link to a champion, similar to Kalista's oathsworn. Another could borrow from Kindred and allow you to pick from the 4 other people on your team via portraits.

But also we could even see Skillshot Healing, where you have to HIT your teammate to heal them. No support currently uses Skillshot heals!

And then I thought: What if they made it so that the projectile's AoE radius decreases the further it travels? Thus a support right next to you can't miss the heal shot(It's a big, shotgun blast of heals), but the further away the more narrow. Then you could even make a support with a heal that can go from like Dragon to midlane, with a pixel perfect range at the very end.

What sort of highend plays could you see from something like that?

I also thought about a Support whose ultimate is to "Mount" their ally and ride them, either taking damage for them or possibly even being able to fire off spells while on their ally.