Auriel is a ranged support that uses short buffs to help her teammates. Her (Q) ability is especially powerful with the basic attack heroes, like Thrall or Hammer. When solo, it gives Auriel some damage presence, but because of the reduced cooldown mana problems may be real. I imagine Strength of Hope is to give some clear indication - some light rays arround the affected target or something like that. Angelic Bulwark might seem a little underpowered when not used on Auriel herself, but good timing and using it when enemies release their big guns can lead to some serious damage. Spell effect should be clear as well, because enemies should have a chance to change the focused target. And to make it clear, Angelic Bulwark reflects unresisted damage, otherwise self-using would seem like an intentional nerf. Heavenly Hymn is a powerful utility, but still requires some game knowledge to use. Heroic abilities are Auriel's significant assets. Sacred Circle can make some AoE useless, but I imagine the actual circle would be much smaller than empowered Flamestrike or Gravity Bomb - you'd be able to save two buddies tops (I'm thinking about the targeted area like regular Flamestrike or Lunar Flare). Swansong comes after my realization that supports often fix the mistakes other players do.
Generally, based on my concept, she'd have follwoing cons and pros:
Pros:
+ Universal support: granting additional damage, dispelling negative effects and heals.
+ Sacred Soil is the only way to counter some AoE spells, like Flamestrike, Mosh Pit, etc.
+ Swansong can potentially fix the mistakes or the bad plays on the team's part.
+ Capable of solo play and solo laning due of additional "self-buff" part of her basic abilities. Can be used as pseudo-assassin as well.
+ She shouldn't have much mana issues: trait is free, long cooldowns give enough opportunity to restore mana. Some talents and solo play may affect that.
+ Ranged.
Cons:
- Cannot directly affect enemy players.
- No CC.
- No AoE, which means invisible heroes remain a problem (should you not spec into Clairvoyance).
- Long cooldowns.
- Limited mobility.
Character statistics, spell power and some other numbers are matter of tweaking and balance that requires game knowledge that I don't posses. Obviously, it's all for fun.
Heroes of the Storm Build Guides
In order to balance it out, I suggest giving her trait a mana cost, so the player needs to decide if it is better to be healing teammates or to be actively attacking enemies, instead of feeling like there isn't a price.
Overall, I just love your idea. A support with limited cc, no aoe but strong heal and some damage. I just feel like it would be really cool if her skills could interact with enemies a bit more, to make playing her more enjoyable for non-support mains.
Hero definitely has some interesting mechanics, I'd change the name of sacred soil to sacred ground or something of the sort; since you arent always fighting in soil, unless she summons soil--which sounds kinda meh :P.
I guess that makes sense :) Something like 'circle' will sound more angel-ish.