Hearthpwn

I love the smell of AOE in the morning.

I've run this into enemies for the +3 on a Lightspawn.    

example:  I had Pint-Sized Summoner coined on T1.    The Mage for some reason used Frostbolt on me.    With the summoner out I was able to get this on turn 2 and a Lightspawn on turn 3.  Mage played a Sen'jin Shieldmasta.  I gladly traded the summoner and the cultist for it (in that order).  With nothing blocking hit the light spawn was now a 8/8 and was buffed with a single Divine Spirit taking the Mage down enough they conceded.

Make sure you plan where the buff goes if possible.   

Many good priest and priest-like cards can use the +3 health.     A few the come to mind are Lightwarden and (2h), [card]Northshire Cleric[/card] (3h).   Taunts can also generally use more health. 
 

Haven't seen it much and not impressed by it.    I was a Priest and I was playing against a Mage.   Turn 10 they played Deathwing.    They dropped 6 cards for this.   Yes it took out my heavily damaged 2/20 Northshire Cleric which was behind a Shieldbearer and a Temple Enforcer.

I has 2 cards one was Shadow Word: Death.    They were losing 8 to 20-something.    I'll admit is was a gamble for them, but with this card you need to watch for removal.   Once you drop this you are top decking.