Pros:
Great support
Lots of CDR
Can restore her own mana
Global heal to all her teammates
Gives bonus armor and magic resist
Lowers Magic Resist of enemies

Cons:
Squishy
Gets targeted
Kind of gets shut down when silenced, stunned, or taunted.
Has to decide who tsave

Soraka is a pure support character. She is meant to protect the carries and heal the tanks when needed. She is pretty difficult to master, but you will get the hang of it. She is loads of fun, but you need to be able to react quick and make logical decisions. I hope you will enjoy this build and playing her, as much as I do ^^.

I get the flat health quintessences for some early health in the beginning so you don't die instantly and have more surviviability. And the mana regeneration runes are just mostly for early game, so you can stay in lane longer and have enough mana for your heal. The Cooldown Reduction Runes are always useful in the beginning so that you can spam your heal and infuse faster, especially when you need it.

I go 8/1/21 for my masteries. I get the cooldown reduction, but not the magic penetration because the magic penetration is pretty useless on a support. I get 21 on utility getting mana regeneration, cooldowns, and summoner spells masteries. I get one point in the armor because there is no other place it is really needed so I put it there, for extra armor which is always great.

Starcall- A area of effect skill used to farm minions and damage opponents. Also lowers Magic Resistance, but you're a support and should focus on supporting your team, so I max this last.

Astral Blessing- Your most useful skill. Used to protect your carries and you should use it whenever you can during team fights. It also gives whoever you heal some bonus armor, so that they can be tankier. Sometimes you need to make the decision of saving the heal for baiting or who to heal. It heals for quite a lot too.

Infuse- A skill that restores mana to yourself, or sharing it with a teammate. It also silences and damages enemies. That means it has two effects in one skill, which is pretty awesome when you think about it.

Wish- Your ultimate, which is a global heal, to you and your whole team. You must have map awareness to use it. Your ultimate can be used to save your teammate who's about to die from getting ganked or dived. In team fights, it can heal your whole team and you can also combine it with your astral blessing. So be very wary and find the right time to use it in teamfights. It has a pretty short cooldown.

I prioritize your W which is your heal, first because with it, you can heal your teammates and give them bonus armor during laning phase and team fights. I prioritize E which is your infuse second so that you can restore your mana and use your heal mroe often. I get a point in your ultimate whenever you can. When your heal is level 4 though, I bring infuse to level 4 with it. Then I max out your heal and then get another point into your ultimate. Max out infuse afterwords. Put points into your starcall until you're able to put a point into your ultimate.

Skill Sequence

W E W E W R W E E W R E Q Q Q R Q

Start with two faerie charms just for some decent early mana regeneration in the beginning. As soon as you have enough gold, go back and buy your philosopher stone. Go back to lane and when you have enough for your other philosopher stone, go back and get that one. After,I pick up some boots for some movement speed. Then I get two kage's lucky picks for the ability power and the gold. As Soraka you rarely get much last hits and you need a lot of gold. So I buy all these for the gold. I buy Ionian boots of Lucidity, for the Cooldown reduction. You really don't need any other boots, except maybe some mercury treads, but I find the early cooldown reduction more useful. Afterwords pick up your Needlessly large rod, whenever you have enough. Turn that into rabadons deathcap after for some major Ability Power. After, turn one of your kage's lucky pick into a Deathfire's grasp. That gives Cooldown reduction, ability power,and an awesome active which can lower enemies health pretty well. Then turn one of the philosopher's stone into Shureiyla's reverie. That gives you max Cooldown Reduction and it gives you health and mana regen, as well as health. It's active is great and you can help your teammates move faster to escape or to chase down. Grab a Zhonya's hourglass afterwords for some armor and more ability power. It's active is quite useful to survive through stuff. Finish it off with whatever you think will do the best against their team if the game gets that far.

Clairvoyance- The summoner skill every support should have. It's basically a free ward every 35 seconds. You can use it to spot ganks, or to peek into their jungle. You can also use it to look at Dragon and Baron to see if they're doing it which is quite useful. It's cooldown is actually like 45 seconds, but since it lasts like 10 seconds, it's a free ward every 35 seconds.

Flash- Since you are the support, you will be targeted by the enemy team and this helps you to escape from them and be able to re-position yourself away from the enemies during teamfights. You can also use flash to get away and then run back into the fight away from the enemies, but in range to heal your team. You can also use flash to get TOWARD your teammates and be able to heal them, which might save them at the last second.

Early Game: You should play safe and try to last hit as well as you can, unless you're in lane with a carry. If you are laning with a carry, you should let them get all the last hits. Heal yourself and your lane mate whenever you guys need it. Also use infuse to share mana with your teammates if they also need it.

Mid Game: I say this point starts when you're about level 7 and have your philosopher stones, your boots, and your kage's lucky picks. You should be starting to team fight and traveling to other lanes to help heal then.

Late Game: Where it all comes down. You should have your Rabadons deatchcap and maybe even your deathfire grasp. You should heal as much as you can during teamfights, so that your teammates wont have to back. Try to get the big golem buff for more Cooldown reduction and mana regeneration too. Share infuse with people who are low on mana and are mana dependent. Try to heal everybody that is low and use it as often as possible.

Overall, Soraka is a champion who is really fun to play, once you get used to her. The satisfaction you get when your teammates tell you thanks for saving them, and when you save your teammates, which angers the other team. She's a great hero to play and has pretty decent survivability with her heals.