The "Inspiration" rune tree seems like the place to go for Utility Support runes, but nothing really seems to reward Support.
I think a new Rune Tree could benefit Supports, or at the very least a few Runes can be added that stack better on Support. The only rune that feels like a Support Rune is "Guardian".
Here's some ideas for Runes that would scale with Supports really well and wouldn't necessarily be more useful for other roles, you might not like some of the ideas- but maybe you like the idea of more "support friendly" runes. Add some ideas! These are just some basic ones to get a general picture.
- Can place an aditional Ward on the Map
- Wards last 10% longer
- Destroying a Ward grants additional Gold and Exp
- Trinket Cooldown Reduction (based on level)
- Using abilities on Allied Champions grants both of you decaying Movement Speed
- Bonus Mana Regeneration while in combat (increases with number of nearby Allied Champions **OR** Unique Takedowns)
- Nearby Enemy deaths reduce the Cooldown for "Trinket Income" effects ( .2 seconds for minion deaths, 2 seconds for Champion deaths)
- Heals on Allied Champions grant additional healing over time
- Shields on Allied Champions redirect damage to the Attacker until the shield depletes
- Using Heals and Shields grants bonus Mana Regeneration for 3 seconds
- Increased Armor and Magic Resistance for each nearby Allied Champion
- Taking % damage within 3 seconds while near an Allied Champion grants a damage immunity shield for 2 seconds (45 second cd)
- Redirect % damage from nearby Allied Champions to you (knights vow in a rune basically but why not.. we got a spirit visage rune "second wind")
Anyways, what are your ideas?