These varieties of healing aren't available to supports so far. Why?
In Heroes of the Storm (and maybe some other MOBAs), there are several different unique varieties of healing that are not present in League. A few include:
- A buff-on-ally effect that gives your ally temporary lifesteal/spell-vamp.
- A direct-target heal that has a significant trigger delay (i.e. cast ability on ally, then they are healed 1 second later).
- Skillshot-based healing.
I have to wonder why these kinds of things aren't on any support Champions at the moment. These would be a great way to create supports who play differently from 
etc.
Let's go over each one.
Temporary lifesteal/spell-vamp buff This one is pretty self-explanatory: you buff an ally and then, for a limited time, they get bonus lifesteal. Tassadar is able to give this effect in Heroes of the Storm, though it is tied to a shield that he also provides. This one is great for trades and for teamfights, but can't be used to patch up your ally from behind a turret; they have to fight to receive that healing.
In League, I would make this "lifesteal" buff spell only allow your ally to lifesteal off enemy Champions, not against Minions, Monsters, etc. This way, it can't be used for conventional lane sustain, and requires that your ally play aggressively and make good trades. Additionally, the total healing from such a buff could also be capped so that it doesn't become broken in late-game, as it could otherwise allow various ADC's to skip a 
etc. I'd also have to make it capable of providing Spell Vamp so it's not super one-dimensional and only usable on AD-heavy allies, but again the Spell Vamp would only work against Champions and would be capped.
Also, I know there were a lot of balance issues with 
having something like this in the past, but if such an on-hit healing buff were localized to a specific support Champion, it'd be much easier to balance.
Direct heal with significant trigger delay This one appears on Rehgar in Heroes of the Storm, where one of his ultimates allows him to hugely heal an ally, but it takes a full second before it actually heals said ally. During this one-second delay, your ally could still be killed before it kicks in. Said delay would be very significant in fast-paced MOBA gameplay, especially in League where there are various ways to inflict Grievous Wounds.
This would still result in somewhat similar gameplay to etc., but that delay would allow for a different power budget compared to the aforementioned Champions due to lower reliability.
Skillshot healing This one is used by Ana in Heroes of the Storm, and again should be fairly self-explanatory. Ana's healing relies on her landing skillshots on her allies, which can result in less consistency compared to direct-target heals. The trade-off is that Ana has more range on her heals and slightly higher potency as long as she lands her shots.
No Champion in League currently uses any sort of skillshot-based healing, probably because Riot doesn't want people getting toxic over players missing their healshots. I say they should ignore that worry, as people get toxic over EVERYTHING nowadays.
A skillshot healer would be a totally new way to play in League, and would allow for a different power budget compared to traditional healers. It's really something Riot should try out.
Each one of the above would be a unique addition to the game, but so far Riot hasn't even entertained the notion of them. I find that rather disappointing. How about you?
post-VGU in Bronze?