Many people see Soraka and think about a fragile new-player-friendly champion that requires minimal knowledge about the game to properly play as her. But this simply isn't true, Soraka is one of the champions that has the biggest impact on the match if played correctly.
While she does indeed have a support'ish style of game, her sustain creates extreme pressure when the enemy needs to go base for purchasing items and refilling mana.

PASSIVE ABILITY

Salvation Soraka gains 70% movement speed when moving towards allied champions below 40% of their maximum health who are outside of Astral Infusion's range.

Basically you go full throttle once someone is dying near you, this allows both faster reach to heal allies, and easier dodging if you're inside or fleeing a teamfight

Q

Starcall Soraka calls down a star at a target location. Enemies standing at the point of impact take 70/110/150/190/230 (+35% AP) magic damage and are slowed by 30% for 2 seconds. If Soraka hits at least one enemy champion, she is also granted rejuvenation for 4 seconds, which restores 14/16/18/20/22 (+10% AP) health per second and grants her 10% movement speed when not moving towards enemies. Starcall takes more time to fall the farther the ability is cast.

Your only self-healing skill, and one of the most annoying pokes in the game. You can use it in a plethora of situations like escaping, poking, healing, zoning, farming, proc'ing, etc. Also, please note that if cast right in front of you it'll fall almost instantly, which is good for dealing with gap closers like Lee Sin.

W

Astral Infusion Soraka blesses a friendly champion, restoring 80/110/140/170/200 (+60% AP) of its health. If cast while under the effect of Rejuvenation, Soraka gives her target rejuvenation for 3/3.5/4/4.5/5 seconds (based on rank of Starcall). Astral Infusion cannot be self-cast, nor can it be cast if Soraka is below 5% of her maximum health.

One of the skills that can actually kill you if used wrong, although it cannot directly kill you, it can put you in danger if used too many in a short time. This skill has a really low cooldown, but considering the cost, it's wise to use it where and when it's really necessary.

You can also use it to help your ally escape from a harsh situation by hitting an enemy with Starcall then using Astral Infusion on him.

E

Equinox Soraka creates a zone at a target location for 1.5 seconds. Enemy champions standing in the zone take 70/110/150/190/230 (+40% AP) magic damage and are silenced until they leave. At the end of the zone's duration, all enemy champions inside are rooted for 1/1.25/1.5/1.75/2 seconds and take 70/110/150/190/230 (+40% AP) additional magic damage.

Even being really hard to proc the latter effect, the fact that this skill is insta-cast is what makes it shine, most of the time you'll be casting this on whoever happens to be nearby, even if the mana cost is relatively high, when you finish your first item hardly you'll ever run out of mana.
Also don't forget to use this skill to protect your ADC from all-ins from the enemy team.

R

Wish Soraka calls upon the stars, restoring 150/250/350 (+55% AP) health to all allied champions across the field. Wish can affect untargetable allies. Wish has a 50% increased heal on allied champions below 40% of their maximum health.

Just like Karthus's Requiem, but instead of killing, you instantly heal ALL allies which are alive, and when cast, if they're below 40% maximum health you'll heal even more, meaning that you can make your team win a otherwise lost teamfight. Seriously, late game you can heal a dying ally back to full health in matter of seconds.

Even though it's counterintuitive to make full AP for a healer support, the fact that her heal increases with AP is what makes it worth.
Being a support doesn't means that you must be 100% of the time only healing and protecting, it only means that your job is to aid whenever needed, which includes defendind the base or killing an enemy (not to be confused with kill steal, which is bad).

Now let's see our pool:

	Spellthief's Edge Can be exchanged for a Doran's Ring for better mana regen, but Spellthief's Edge gives more gold for a faster item purchase.
	Doran's Ring As this guide's Soraka burns mana, can be a wise choice to pick Doran's Ring in some cases.
	Health Potion Buy two of these, it helps so much early game that you will never underestimate it again.

	Forbidden Idol Our main sustain item, later upgraded to Ardent Censer it gives us +50% mana regeneration and +5% bonus to our healing and shielding.
	Sheen I never thought about using this item for Soraka, but I've discovered that it helps SO MUCH zoning the lane, it helps you give your ADC a lot of space for farming since sooner or later people will need to go back to base for regenerating health, with this item they go sooner!
	Boots of Speed A pretty handsome item that allows you to dodge easier, take one as soon as possible but do not sacrifice Forbidden Idol unless strictly necessary.
	Health Potion Again, buy potions, better to be safe than sorry.

	Sorcerer's Shoes The main boot of this guide, gives you raw magic penetration which further increases our damage.
	Boots of Mobility If you need more wee woo then take this item, it allows you to reach even faster your comrades in case you end up being a multi-lane support.
	Ionian Boots of Lucidity Most items on this guide gives cooldown reduction already, but as we took Transcendence it can be a good idea sometimes to take these boots, never know when you will need an extra AP ealier.

	Ardent Censer Hardly any item can substitute this one when it comes to a healer support thanks to the enormous healing 'n shielding buff, this is your main item most matches.
	Redemption One of the default build items, gives you the ability to heal allies within a circle and damage enemies by % max health, pick this item when constantly needing to heal more than one ally.
	Athene's Unholy Grail For every damage you cause you get a stack, increasing your next healing by the number of stacks, as we poke a lot with this build it can be a good idea to take this item.

	Luden's Echo Main damage item, literally explodes whoever gets hit by your skills, damaging nearby enemies, function like Rapid Firecannon but only procs on skills.
	Liandry's Torment The poor trade punisher, gives your spells DoT effect which burns 1.5% maximum health per second during 3 seconds, and if they get their movement impaired it increases to 2.5% maximum health damage (remember that Soraka's Starcall applies slow).
	Rylai's Crystal Scepter If you're having a hard time rooting enemies with Equinox, take this item to apply slow so it becomes a little easier to proc the root.
	Morellonomicon Another DoT item, coupled with Liandry's Torment it becomes a really strong effect as they stack (different debuffs).
	Rabadon's Deathcap Increases your AP by 40% while giving 120 AP. Seriously, it's by far the most essential item to any caster champion, and will give you such powerspike that you'll become a monster on any teamfight.
	Lich Bane Because we took Sheen early game, it might be a good choice to take Lich Bane due to its increased damage, but don't take it unless you're taking the poke path.

100% compatible champion

Soraka matches with every champion in the game, it's very unlikely that you will ever be incompatible with your team.

Laning Phase

When you get to the loading screen is when the match actually starts, because during that time is when you'll start planning your item sequence, so pay attention to your opponents: does they have an APC (Ability Power Carry, not the actual tank)? Does their support play aggro or safe? Is their jungler early-cheeser or late-ganker? All those things will define whether you'll make the normal sequence or rush to get an item. "It's all about MIND gaming!". And it's true! Not everyone considers playing with your opponent's mind, stop to think: WHY is Fiddlesticks such a pain to play against? He isn't tank, nor mana-cheap, not even a hard-CC champion if you stay at AA range! BUT he has great zoning power, just like Blitzcrank, you don't even need to actually cast a skill to make the enemy retreat, just ACT like if you would cast. Soraka is the same case, you must keep applying pressure early game so the enemy will become afraid to all-in you and your marksman knowing that he'll risk being silenced and bursted back.

Skirmishes Phase

Now that the first tower has already fallen, they will begin playing differently than before, while you could stay with your ADC the whole game, it's better not to because while he is at base or dead you have 3 more teammates waiting for assist, do not be afraid to roam all the lanes offering a help to take the towers. BUT always try to stay with someone, Soraka's kit isn't enough to disable someone chasing you. "WHO said YOU could die?". This shall be your mantra when planning which lane to roam, NEVER allow anyone to die besides you, just like those movies and anime where the main character gives everything of himself to protect his allies, play just like that (but don't allow people to abuse your friendship). Tips for this phase: Be the hero; Stay both behind healing and attacking enemies; Help all lanes taking objectives; Always ward whenever you have one.

Teamfight Phase

Lategame, the phase where teamfights break almost everywhere and respawns are slowing down. Let me tell you a secret: know that enemy that explode eveyone? Well, not anymore. Unless you have a 10/0 Draven or Jhin no one will be able to outdamage your healing! The game will be a bit fast now, you'll need to keep an eye at teammates' health at all times, and rush to heal everyone below 40% HP, if you purchased at least 4 items your healing is AS POWERFUL as a fed Karthus's Requiem. Stay with your team, let them know that they can focus on bulldozer'ing the lane while you'll keep them alive.     Objectives at this phase are pretty straightforward: Take objectives; Aid your teammates; Tilt that AP carry; Finish your build.

Sudden Death Phase

The most intense phase of the match, when the time reaches ~40 min one single ace can mark the end of the game. I really don't think that the game will ever reach this phase if you played correctly, but if it ever reaches, keep playing just like you used to at the previous phase, taking baron nashor and elder dragon whenever possible, and blowing up those inhibitors. Unless your team is losing the high ground, everything shall be clean and smooth. Just don't let your team become overconfident, many games are lost due to someone thinking that it's impossible to lose. Keep going until their Nexus is broken, and THEN you can relax and celebrate your victory!

Well guys, I hope that this guide was helpful for everyone wanting to play as AP Soraka, I'm open for suggestions and will try to keep this guide updated.

See ya!

As always, this guide wouldn't be possible without these awesome guys, so they deserve a dedicated section in their tribute:

• Thanks @ jhoijhoi for writing those BBCode guides, I don't think anybody made a markup language easier to learn than you. Also thanks for the detailed review of this guide!
• Thanks to the artists that made those non-banner images, all credit from them goes to their respective creators.
• Also thanks @ jovy for giving me enough inspiration to make this guide's banners, they are only great because of her!
• Thanks @ psiguard for reverting my catastrophic error and aiding the community whenever possible, not all heroes wear capes, eh?
• Thanks to everyone that comented/voted on my guide, you guys gave me the inspiration to keep upgrading and updating it. Much thanks!