It is unlocked at Earthen Heart rank 12.
- U5: Fixed an issue where this ability's graphical effect would be removed when an ally activated the Protective Shell synergy. 
- U6: Reduced this ability's Synergy radius 2.5 meters, and increased the strength of the shield produced by the Synergy to 100% of your maximum health from 85%. 
- U3: This ability no longer stacks if you recast it before the duration expires. We also fixed an issue where this ability was doing 10x damage than intended.