This has been removed from Heroes of the Storm. 


Tier 6 (Hero Level 16)
Each Hero that Holy Radiance passes through increases the healing and damage of your next Holy Radiance by 8%, to a maximum of 80% increase.
Patch changes[]
(Patch September 13, 2016) Note: The tooltip for the Gathering Radiance Talent will now properly indicate the amount of bonus Healing and Damage earned after multiple nearby Allies are hit by Holy Radiance.
(Patch August 9, 2016) Note: Uther has received Custom UI that will display next to his in-game Hero Portrait after learning the Gathering Radiance Talent, and tracks the bonus Healing and damage amounts that will be applied to the next Holy Radiance cast.
(Patch July 12, 2016) Note: Each Hero that Holy Radiance passes through increases the Healing and damage of your next Holy Radiance by 8%, up to a maximum increase of 80%.