Holy Shock is the second cheapest healing spell available to the Holy Paladin, and is significantly stronger and faster than [Holy Light]. With only a 9 second cooldown, it should be used often for both power and efficiency.
[Infusion of Light] grant you specific benefits following a successful critical cast of Holy Shock.
Trivia
In Warcraft III, the Paladin hero's Holy Light spell healed friendly living units and damaged enemy undead units. Considering this, some may view Holy Shock as a variation of WC3's Holy Light.
Holy Shock is one of Uther's passive Talents in Heroes of the Storm, allowing him to use Holy Light to damage enemies.
Patch changes
Patch 7.1.5(2017-01-10): Now damages for 280% of spell power (was 350%).
Patch 7.0.3(2016-07-19): Cooldown increased from 6 seconds to 9 seconds. Damage increased by 66.7%, healing increased by 185.7%.
Patch 6.2.0(2015-06-23): Mana cost has increased by 50%.
Patch 6.0.2(2014-10-14): Now has twice the normal chance to critically strike (instead of having an additional 25% chance to critically strike).
Patch 5.4.0(2013-09-10): Mana cost has been reduced by 50%.
Patch 5.0.5(2012-09-11): Holy Shock's base damage has been reduced, and its spellpower coefficient has been increased.
Patch 5.0.4(2012-08-28): Range against hostile targets increased from 20 to 40 yards. Has an additional 25% chance crit.
Patch 4.2.0(2011-06-28): Mana cost has been decreased to 7% of base mana, down from 8%.
Patch 3.0.2(2008-10-14): Cooldown reduced to 6 seconds.
Patch 2.4.0(2008-03-25): The healing, damage, and mana cost of this spell have all been increased.
Patch 2.0.1(2006-12-05): Cooldown reduced to 15 seconds, down from 30 seconds.
Patch 1.10.2(2006-05-03): Bug fix: Now guaranteed to crit when used offensively while Divine Favor is active.
Patch 1.9.0(2006-01-03): This spell can now heals friendly targets. Mana cost reduced. Increased the coefficient gained from spell damage and healing.
[Holy Light]. With only a 9 second cooldown, it should be used often for both power and efficiency.
[Infusion of Light] grant you specific benefits following a successful critical cast of Holy Shock.
Patch 7.1.5 (2017-01-10): Now damages for 280% of spell power (was 350%). 
Patch 6.2.0 (2015-06-23): Mana cost has increased by 50%. 
Patch 5.4.0 (2013-09-10): Mana cost has been reduced by 50%. 
Patch 4.2.0 (2011-06-28): Mana cost has been decreased to 7% of base mana, down from 8%. 
Patch 3.0.2 (2008-10-14): Cooldown reduced to 6 seconds. 
Patch 2.4.0 (2008-03-25): The healing, damage, and mana cost of this spell have all been increased. 
Patch 1.10.2 (2006-05-03): Bug fix: Now guaranteed to crit when used offensively while Divine Favor is active. 
