This spell is a part of the Spiritual Sight spell chain and can be found in the Spiritual Sight rune stone.

When this spell is created a spirit forms around the target of Spirit's Strength. It copies your Soul and doubles it with Soul being its life force. Each time you are attacked, you may have the spirit take on up to 90% of the damage which will deplete from the spirit's Soul life force. So if you got attacked for 100 damage, you can have the spirit absorb up to 90 of that damage, that 90 would come from the spirit's Soul. If you had 100 Soul when you created the spirit, the spirit would have 200 Soul as its life force, so that 90 would drop the spirit down to 110. You can also take up to 20 Soul from the spirit to restore your Soul per support action, however doing so would drop the spirit's Soul by that amount. Once the Soul of the spirit is depleted, or once you have gone to sleep, lost consciousness, or died, the spell will end. 

Stat Cost: 40 Soul
Casting Speed: 4
Duration: until depleted or caster asleep, unconscious, or dead
Range & Area: 1 target or self
Protection Spell
Success Rate:  45
Max Success Rate:  75

This is a Tier 4 spell

Level 1: 100/200