Quick writeup for ARAM Soraka: designated Warmog's holder.

In patch 14.10 Warmog's was buffed from 750 HP to 1,000 HP.
So Warmog's now only requires 300 extra health for passive to activate.
Usually, you will have enough gold to buy Warmog's and extra HP around level 8.

• 160 HP from 2 scaling HP shards at level 8.
• 150 HP from 1 ruby crystal

That gives 310 HP.

Tear, Presence of Mind, AND Clarity is recommended, otherwise you will be limited by mana after Warmog's comes online.
Since Soraka can't make good use of any Precision path keystones, Precision will always be the secondary path.

Resolve Path
Most healing, least damage.
This is usually the path to go.

Keystone: Guardian
Row 1: Demolish > Font of Life
Row 2: Bone Plating
Row 3: Revitalize
Font of Life used to be great, but was reworked on 14.10 to heal yourself and 1 ally for a flat amount upon slowing/cc-ing an enemy champion (20 sec cooldown).
The ally healing is pathetic compared to the old Font of Life, and the self-healing is pointless as Soraka's health should be topped off by Warmog's anyway.

Sorcery Path
Less healing, less shielding, more damage.
Only go this path if your team is severely lacking damage or magic damage.

Keystone: Aery
Row 1: Nullifying Orb ~ Manaflow Band
Row 2: Transcendence
Row 3: Gathering Storm ~ Scorch

Domination Path
Build acceleration.
With Resolve path's Font of Life getting nerfed and Warmog's costing 800 less gold to get online, the Domination path might be worth taking solely for the extra gold from Treasure Hunter which can make it much easier to rush online.

Keystone: Dark Harvest
Row 1: Cheap Shot
Row 2: Eyeball Collection
Row 3: Treasure Hunter
Treasure Hunter earns more gold by level 8 (when you get Warmog's) than all of the Inspiration path runes combined.