Welcome to my first build (so be nice >_< ), which is for Soraka. I made this build after the support rework where supports became less of a support and more active in battles. This means that the cooldowns have been increased on Astral Blessing but the healing aspects have been reduced.

I persnally prefer to run Soraka on 0/9/21. This is because the utility tree allows for a longer clairvoyance spell with a reduced cooldown which can be very useful in protecting yourself and teammates against ganks and also for checking baron and dragon if you do not know where your enemy has vanished to. Also, the utility tree helps with movement speed, mana regen., cooldown reductions and your experience & gold gain. This is needed as when you play support you often do not gain many minion kills so the extra gold can come in handy.

I run with 9 points in the defensive mastery tree so that the basic levels of armour and magic resistance are increased which means that you aren't as squishy, especially early game when you could be getting targetted for possible free kills. Also the health regen. can help you stay in lane longer and will leave Astral Blessing free to use on the champion that you are babysitting.

I don't put any in the offensive mastery tree because you are Soraka: you are there to heal, not attack!

I've based my rune choices on early game sustainability: the mana marks and the mana seals means that you have a higher base mana pool from the start of the game. Some people would argue that you can give yourself mana by using Infuse but it is better to leave that availible for the character that you are babysitting as they are the one who will be dealing the damage in your lane. Also, leaving Infuse free to use on the enemy allows you to silence them before thehy can attack, which could leave them open to be a free kill by your team or could save the lives of your allies.

Since cooldowns have been increaed on Infuse and Astral Blessing I have decided to use cooldown reduction glyphs to help counteract this. It doesn't take your cooldowns back to how it used to be before the patch but it helps.

Health quintessences mean that you have a higher base health, which means that you can withstand more attacks than you would be able to without them before having to either heal yourself or recall. Again, this leaves your spells free to babysit your allies in lane.

With the skills, I find that maxing out the support spells is the most important aim. Therefore, I start with Astral blessing and alternate between this and Infuse, putting a point in Starcall at level 3 to help your laning partner with farming and points in Wish when prompted at levels 6, 11 and 15. By doing this it means that you are ready to support your team with at least level 3 Astral Blessing and Infuse when laning stages end.

I like to run with, and suggest, that the summoner spells that you should run with are Clairvoyance and Flash. There are spells that could also work but I prefer these.

Possible Summoner Spells:
[*] Clairvoyance - gives vision for your team, can prevent ganks.
[*] Flash - allows you to escape from sticky situations where you have been ganked or are getting focussed down
[*] Heal - Useful spell to take as it provides your team with an extra heal but it doesn't restore a lot, but could save a life
[*] Clarity - Useful for a heavy mana-reliant team. Can allow them to use more skills in teamfights before having to back out.
[*] Ghost - It can always be useful to be able to move around a lot faster but do you need to be any faster when you have Boots of Mobility?
[*] Teleport - Being able to get back to lane quickly or moving to where the teamfight is about to take place can be useful but always ask yourself whether there are better summoner spells out there.

Skills you May Consider Taking:
[*] Fortify - If a tower is being pushed then you may be able to save it with this spells but always ask yourself whether you plan to save towers or save people, but it shouldn't be completely ruled out.
[*] Exhaust - Your team are close to killing an enemy champion but they just get out of their range and escape with a smallest amount of HP. Could be avoided by using exhaust on them but, like fortify, consider what you deem more valuable for your team.
[*] Ignite - See "Exhaust" as it's basically the same thing.
[*] Cleanse - Basically a Quick SIlver Sash or a Banshees Veil but as a summoner spell. Could allow you to escape against that CC-heavy team or allow you to heal your dying teammates, but as I have stated with the rest of them consider what you see as more important for your team composition.

Skills You Shouldn't Take:
[*] Rally - I have only ever seen it used once before but it had hardly any effect. You can take much more useful skills than this.
[*] Revive - You can revive yourself instantly whenever you die but you should be staying far enough back to not be getting killed all the time, apart from the occasional gank or focus down. Take a more useful skill than this.
[*] Smite - Do you really plan to be jungling with Soraka? Really?

I start with a Faerie Charm for the mana regen, 2 health pots so that you don't need to use Astral Blessing on yourself and a sight ward to place in the river when you feel like it will be needed. The extra gold you leave the fountain with will mean that you can get your first item earlier than if you spent all your money.

Early Game:

Aim for an early Philosophers Stone: this will give your a good mana regen for the early game and the extra gold passive will help you be able to build. Next, you should buy your speed 1 boots so that you can move around a little bit faster and will give you more of a chance at dodging skillshots that are coming your way. Heart of Gold should come next, allowing another extra gold item (which do stack: you can't stack the same item but you can stack different items with this passive) and also giving you health regen. After this, you want to upgrade to your Boots of Mobility for enhanced movement; they will allow you to traverse the map quickly so you can ward a large area very quickly, and will also aid you in escaping if the enemy decide to dive for you.

Mid-Game

At this point, you will be wanting to be warding and ward hunting, so buy an oracle and take out any enemy wards that you find whilst placing your own wards in strategic places to allow sight of the enemy at most times when they travel through the jungle. At this stage you may want to upgrade your Philosophers Stone to a Shurelya's Reverie for the cooldown reduction aspect of the item (note that you will lose the gold/5 passive when you do this). The enemy will also be hitting a lot harder now so purchasing a Warden's Mail will increase your armour and prepare you for buying a Randuin's Omen later in the game. A Negatron cloak will also give you MR and prepare you for an Abyssal Scepter later in game.

Late Game

At this point of the game you want to be fairly tanky so that you can survive in most teamfights and so that you are not a prime target that the enemy know can be taken down easily. Now, you buy your Randuin's Omen which has a passive of having a chance of slowing enemies that hit you, as well as increasing your armour. Next you should buy, depending on whether it is the AD or AP dealing the most damage in the team, either a Frozen Heart for against AD damage or a Force of Nature for against AP damage. Personally, I prefer to go for the Frozen Heart because of the cooldown reduction and the extra armour as this means that you should be able to take tower aggro whilst your team take it without minions which can be very useful if your tank died in the last battle. An Abyssal Scepter is always my last item as it it useful to have some AP this late in the game so that you can assist more in teamfights and you may as well make use of the Negatron Cloak you bought earlier for some cheap MR.