Heals, heals, and more heals.
Empowered abilities and resource manipulation
Your attacks and abilities send Aery to a target, damaging or shielding allies.
Hitting enemy champions with a spell grants maximum mana.
After reaching 250 mana, Manaflow Band restores 1% of your missing mana every 5 seconds.
All movement Speed bonuses are 8% more effective on you.
Your first ability hit every 20s burns champions.
Durability and crowd control
Heals and shields are 5% stronger and increased by an additional 10% on targets below 40% health.
After taking damage from an enemy champion, the next 3 spells or attacks you receive deal less damage.
+5 AD or 9 AP
Summon Aery is a great option for Soraka both offensively (with autos and [Q]) and defensively (with [W]).
Manaflow Band is a great option here for Soraka because you're going to want to play aggressively in lane early spamming [Q].
Celerity on Soraka allows you to position yourself safely in teamfights and skirmishes so that you're able to continue pumping out heals.
As a added benefit, when your passive kicks in and you get the Bonus Movement Speed towards low allies, Celerity will grant a bit more extra AP to empower those heals.
Scorch allows you to dominate the lane phase if you're able to consistently land your [Q].
Because you're going to be healing so much over the course of the game, Revitalize gets fantastic value, especially if the target is low health.
Bone plating allows you to survive all-ins and early trades where you might otherwise die.