Always good to have mana regen in the start on soraka

You always need to ward

Mana and hp regen always needed and u get gold faster

So you faster get to spot for supporting

If you need to run just use this and run plus you get mutch lower cooldown and more health and health and mana regen

Make it harder for the enemies to kill you and you will get more health health regen and armor

Buff up your and you teamates magic resist so you dont need to heal same mutch and give you more AP

Buff up your health armor and magic resist and your teamates magic resist armor and attack damage so you dont need to heal same mutch

Give you more mana and armor and cooldown reducetion and make your enemies attack speed reduces by 20%

Always good to have an escape spell

So you can ward for the jungler or if someone is SS

You will always need magic resist as soraka so thats why you use this 2 runes

Soraka got very long cooldown on her spells thats why u need mutch cooldown reducetion