Just a little of what I've learned while playing support Soraka.
It's definitely not the only way to play, but it has worked extremely well for me.
Just thought I'd share, hope you like it! (:
Pros / Cons
+ You will keep your team up for a long time, which makes everyone happy (except the enemy team).
+ Great at poking/silencing. Do this to put pressure on enemy team early game. Sling those bananas!!
+ Minion farming won't be a necessity with this build's increased gold. Just gather those assists! Profit.
- Squishy early game, but you're a support not a bruiser, play it safe/smart.
- The enemy team will usually always focus you first. Soraka has a pretty good range tho, make sure you stay back behind your team, ready to use heals, silences or shurelya's to get them out alive.
Flash - I've found Flash to be a great choice for Soraka. Fights can get a little hairy, and we all know ganks suck... you can't heal everyone when someone decides to bum rush into the enemy team. In those moments, when the *cough* noob *cough* gets murdered and you're alone... flash can mean the difference between getting chopped to oblivion or living to sling another banana.
Heal - I also take Heal on Soraka. People can get a little hasty when they know they have a pocket healer at the ready, without realizing "HEY! Maybe this person has COOLDOWNS." When all your CDs are blown and a team fight is under way, a quick Heal should keep everyone up while your abilities have time to tick. (:
I generally try to go Ability Power and Cooldown Reduction with my support Soraka build. The more often you can pop your heals out, the better.
I start with Faerie Charm, Sight Ward x3, and Health Potion x3. I'll sometimes mix the amount of Sight Ward and Health Potions up depending on who I will be laning against. High damage = more pots. I try to only use Astral Blessing on my lane partner. I will only use on myself when absolutely necessary. This is where the pots come in handy. I haven't found that I have a problem with mana with Soraka, so Mana Potion aren't needed.
My next purchases are usually Amplifying Tome >> Mejai's Soulstealer >> Philosopher's Stone (in that order). Although I will sometimes take the Stone first if I find the enemy team is being more aggressive, for the extra mana regen. I find it's important to get Soulstealer early in-game for the AP stacks. The sooner you get to 20 stacks, the better. The added AP and CD reduction is a great advantage early-mid game.
Next purchases should be Ionian Boots of Lucidity and Shurelya's Reverie. The upgrade on boots is great for both added speed (Soraka is so slooooow, I feel anyway heh) and cooldown reduction (Yay!). Shurelya's is a MUST HAVE for Soraka in my opinion. More CD reductions ( we love those!) and it's active can really help get your team out of some hairy situations!
Hextech Revolver should be your next purchase and should be upgraded to Will of the Ancients asap. WotA will give yourself and your team Spell Vamp, which I've found to be incredibly helpful.
What's Spell Vamp and why is it important? Spell vamp, my friend is kind of like Life Steal only regeneration of health is based on damage done by your champions abilities. Any damage done by surrounding teammates, whether it be item effects, abilities or summoner spells will give that champion health regeneration determined by the amount of damage done.
If the enemy team hasn't surrendered yet, my final purchases are Rabadon's Deathcap and Deathfire Grasp. MOAR ABILITY POWER PLS. I don't use the active on Deathfire much but I found that the ability power/cooldown reduction combo is too great to pass up.
If you've used this build, send me a screenshot and I'll add it here!
Hope you enjoyed my guide! If you didn't, tell me why and I'll try to fix it!