Hearthpwn

Overview:

As is evident from the name, this deck is designed to dish out some mean spell damage as a Priest. It contains a fair share of + Spell Power as well as some Taunt minions to cover for them. There are also some draw cards to speed things up.

Basic Playstyle:

I am calling this a nuke deck, but as you can see there are only 4 direct-damage spells: Mind Blastx2 and Holy Smitex2. To account for this, there are many minions in this deck that will hopefully allow it to operate as a competitive aggro deck until you get a high-damage combo. Also, Auchenai Soulpriest can be combo'd with Greater Heal to dish out a pretty mean combo that scales on the size of your opponent's hand. The beauty of this combo is that it can be performed in a single turn at a relatively cheap cost (6 Mana total). There are also some other pretty strong combos in this deck.

Notable Combos:

• Knife Juggler + Imp Master Should allow you to get some minions out there and deal some decent damage while you're at it. If you can drop a Defender of Argus down in between two garbage minions and spare some Mana to use your Hero Power periodically, then you should be able to survive for at least two or three turns easily.
• Prophet Velen + Mind Blast or Holy Smite + a little bit of Spell Power = A fair dose of damage.
  If you have the Auchenai Soulpriest out on the board as well, Velen can substantially buff the damage of Greater Heal.
  NOTE: As the designer of this deck, I personally would only play a Soulpriest if I was ready to dish out a Greater Heal damage combo. Otherwise, I would keep them in my hand so I can toss out heals with my Hero Power.
• Divine Spirit + Inner Fire = Substantial buff to any minion, regardless of what it is.
• Prophet Velen + Divine Spirit + Inner Fire = Quite an angry old man.
• Malygos + Divine Spirit + Inner Fire = 24/24 angry dragon.
  NOTE: Malygos can be juiced to a 48/48 if 2xDivine Spirits are used. Unlikely, but still crazy.
• Faceless Manipulator used to copy either Velen or Malygos will stack their affects, quadrupling damage/healing or adding +5 more Spell Power. If played after either one of them has been buffed by the above combos, GG.
  NOTE: If 2x Faceless Manipulators are played to copy an existing Prophet Velen, you're looking at an 8x increase to spell damage/healing, meaning Holy Smite now does 16 while Mind Blast now does 40. Epic.
  OR, now bear with me here, imagine your opponent has a full hand of cards and you have both Manipulators and Velen down. You then drop Auchenai Soulpriest and lay out a Greater Heal to deal 160 damage!!! Hilarious!

Notes:

• The high-damage combos stated above are going to prove quite difficult to attain, because it requires that you stay alive until the late-game. Hopefully your aggro minions, Taunt, and your Hero Power will keep you alive until then. 
• The Divine Spirit + Inner Fire combo can also be used to increase the life span and board presence of one of your smaller/mid-range minions in a defensive role as well.
• Hogger is added because he's the perfect card to cover for this deck with his constant spawning of Taunt minions.
• Ancient Mage is added as opposed to a cheaper Dalaran Mage or a more useful Azure Drake because I don't expect to have trouble placing him between two minions, allowing for +2 Spell Power for 4 Mana.
• Mass Dispel is added because in my opinion it's easily one of the most powerful Priest cards there is, and it draws you a card.
• Lastly, it's important to note that I did not put Greater Heal in this deck exclusively for damage-dealing when combo'd with the Auchenai Soulpriest. It's role as a healing spell is not to be overlooked, and it can definitely be a life-saver should you get unfavorable draws.