Tweaking Support Keystones, a bit
When I say "Support Keystones" I have two keystones in mind. Guardian and Summon Aery.
Currently Guardian is pretty much the only one that is EXCLUSIVELY a support keystone. That is to say that it is completely useless if you are not within 175 units of an allied champion, or if you are not within range to affect an allied champion with a uni-targetd ability (if you even have one).
So basically this keystone has no business on anyone but a tank support, unless you are planning on doing a lot of roaming/ganking, or just waiting until you reach the team fight phase.
My idea is to change this ability to put you on guard once per 60 seconds, (or longer), however the cooldown decreases by an additional 0.5 second per second you are within 175 units of an allied champion, and by 1 seconds (or more) for every time you affect an ally with a uni-targeted ability.
When off of cooldown, this would continue to work exactly the same as it does currently.
I only increased the cooldown by 50% because I don't expect it to always be easy/beneficial to stay within 175 units of an ally consistently during laning. If you are able to do so for 30 seconds, you would return the cooldown to 45 seconds, which is the current cooldown for this keystone. I also suggested the added cooldown for affecting allies with uni-targeted abilities because many supports have buffs, heals, and shields that they can use on their ally during laning which will keep this cooldown low without having to be on top of them.
Now, how does this help other roles? Simply, a top, mid, and jungler now has the ability to guard themselves without being near an ally every 60 seconds. Pretty simple, but opens this keystone to a lot of champions.
For Summon Aery, ..
I actually feel like it has the opposite problem as Guardian, and that is that it is a support keystone that is a little too useful to everyone.
What I would do is make it so the player benefits from alternating between the offensive and defensive uses of Aery.
I would decrease the base damage and shield figures (mostly damage) so when a player does not have the ability to alternate uses, Aery is less effective. For example, when champions do not have any shield or heal abilities, they are only applying Aery to deal bonus damage. While this would still be available, it would not be as strong, and they may decide to turn to Arcane Comet. The unique cooldown mechanic could still make Aery better for some, which is okay.
While laning with an ally, a support could use this to poke their opponent, then gain an empowered shield for their ally. Having shielded their ally, their next use of Aery to deal damage to their opponent will then deal extra damage. However, if they poke and poke, or shield and shield, it will not be as strong.