Hearthpwn

A little bit of background

Originally inspired from Shadow Fatigue by RoqueGB, this deck is built solely for the purpose of running a deck with Shadowform that is not just a lesser variant of any standard Priest decks, yet actually feasible and fun to play.

I'd be honest; this deck is quite hard to play. You'll notice that this deck is not a Shadowpriest deck, but a Shadowform deck. There are no Mind Blasts, Shadowbombers, or even Prophet Velen. Rather, this deck is all about defense. You are required to play the right cards at the right turn, especially in early games until turn 5. Otherwise you'll lose health to the point you cannot recover after all. But if played correctly, this will surely outlast many foes, even against warriors with 30 ~ 40 stacks of shield.

Shadowform

Shadowform, the heart of this deck, is a unique spell that changes your hero power. After the first cast, you effectively get Holy Smite with 1 increased mana cost every turn, at the cost of losing the ability to heal. After the second cast, you get free Darkbomb without additional mana costs. That means, your hero power becomes extremely mana-efficient and card-efficient, so that you're supposed to use your hero power almost every turn.

In a way, this card is similar to Wild Growth terms of mana control. While Wild Growth allows tempo advantage with fatty cards at the cost of early game tempo, Shadowform makes a card advantage instead. You're going to play cards with two mana less every turn, yet as efficiently as playing in mana curve. That's why we don't play draw cards like Northshire Cleric. You simply cannot use all you cards with utilizing the ping at the same time (besides, you cannot draw with Northshire Cleric when you don't have a heal).

An effective consequence of this draw-less deck would be the fatigue decks. Thus, the major winning condition of this deck is fatigue; Your primary goal is to endure and outlast as much as you can with your mighty 2~3 damage ping and efficient removals, which is another specialty of Priest class. As result, you'll outlast almost any decks with huge card advantages, given that you have succeeded to survive.

I assume that you're already familiar with basic combos of Shadowform (e.g., HP-Shadowform-HP combo). If you're not, just remember that your hero power is refreshed once when you play Shadowform.

This deck is...

Strong against: Classic aggros (Zoolocks, Mech mages, Midrange Hunters) and Control decks (Warriors, Demonlocks)

Weak against: OTK decks (Almost auto-loss against Ancient Mage Freeze Mages), Midrange Druids and Oil Rogues

General gameplay

Your early game consists of board control and survival, while seeking the chance to safely play Shadowform. Even if it seems right to use Shadowform as early as possible to benefit its effect from the early games, it might lose you the board control at turn 3~5, which in turn costs your 10~20 health until you gain access to AoEs (e.g., Lightbombs) to recover. Try to use Zombie Chow, Explosive Sheep (for zoo) and taunts (e.g., Deathlord, Sludge Belcher) for board control. There are many early-game advantages so use it accordingly. In mid-game, you'll have to deal with creatures by using your ping and AoE. In general, focus on card efficiency, rather than mana efficiency.

Key cards

• Shadow Word: Pain and Shadow Madness: Early game removals. Note that unlike the usual gameplay in priest, you don't have to use them against something like Acolyte of Pain, Armorsmith which does not really affect your early survival.
  
  
• Doomsayer: Great for starting hand. Serves as a cheap removal or a taunt. Do not expect to have a jackpot with this card as it does in Freeze Mages. Just removing something over 2-cost is enough. Hard counter against Mirror Entity and Sylvanas Windrunner. Irreplacable.
  
  
• Explosive Sheep: Not only used by itself, it can be used as a mid-game combo (Sheep + Lightbomb) that fends off most of the enemies. It is countered only by Silences. Hard counter against Mirror Entity and Sylvanas Windrunner. Irreplacable.
  
  
• Coldlight Oracle: The only draw card that does not interfere your winning condition (fatigue). You might use it to mill your opponent's hand, but don't delay using it for that purpose. The main purpose of this card is to draw removals and Shadowform in a stable manner. You're supposed to get your two cards that answers more than two cards given to your opponent. It is kinda replacable with other draw mechanics, but then they will lose you in long-term games against such as fatigue decks and warriors.
  
  
• Deathlord: One of the best card to reliably make a chance to play Shadowform. Its deathrattle can be usually answered by bunch of removals we have. Also it fatigues the enemy faster. It might be bad against control decks with cheap removal (especially Warriors and Priests), but it wins against almost every other decks, especially aggros. Even getting fireballed is not too bad since it prevents your face getting fireballed, which is actually very important in long games. Irreplacable.
  
  
• Antique Healbot: Your lifesaver. Irreplacable. Keep in mind not to use in early games against decks that usually runs Alexstrasza (e.g., control warriors, freeze mages).
  
  
• Holy Nova and Lightbomb: Your AoEs. Don't hesitate to use them against pile of 4-attack minions (Shredders, Yetis) since they are hard to remove with your other priest removals. Lightbombs are essentially irreplacable. Holy Nova might be replaced with something like Abomination, but it is not recommended.
  
  
• Holy Fire: Counter to various 5-health minions that is dominant in current meta (e.g., Fire Elemental, Ancient of Lore or Mechanical Yeti). Also serves as an additional heal. Irreplacable, but it can be omitted if the meta shifts to extremely zoo-oriented (like in early Naxx).
  
  
• Vol'jin and Mind Control: These are mainly included to counter 4-attack-high-health minions like Ysera and Malygos. Vol'jin has great synergy with Shadowform, so consider it as a one-time removal spell with 7 mana.
  
  MC is also great for dealing with deathrattles such as Sylvanas Windrunner and Sneed's Old Shredder.
  
  Vol'jin is replacable with second Mind Control, but it will severely hurts you against priests and handlocks, since it reduce your answers against things like Injured Blademaster, Twilight Drake and Deathlord with Velen's Chosen.
  
  
• Harrison Jones: Counter against rogues, warriors, Jaraxxus and Doomhammers. Usually we don't want to draw cards by ourselves (except with Coldlight Oracle), but this is an exception since those weapon-oriented plays are something that our removals cannot answer. Replacable with Acidic Swamp Ooze.

Why not XXX?

• Auchenai Soulpriest and Circle of Healing: There are not much combo pieces (like Injured Blademaster or even Wild Pyromancer or Northshire Cleric) at all. Besides, we don't have much draw in this deck so there's little room for strict combo. You might include one Auchenai as a semi-Shadowform, but it is not recommended since it can be easily removed next turn. You'll have to wait until turn 6 to get a guaranteed ping with it.
  
  
• Cabal Shadow Priest and Mind Control Tech: Too heavy (cabal) and situational (mc tech). AoEs and pings are much better answers against swarm of enemies since we don't have much cards to get board advantages over the opponents.
  
  
• Alexstrasza: Usually there's no need to burn down the opponent, so it is mostly used for heal. But then, it does not help you much against strong finishers (e.g., Druids, Warriors, Oil Rogues and Freeze Mages), neither it helps board control.
  
  
• Kezan Mystic: Along with Harrison Jones it was something I have experimented for some time. But unlike troublesome weapons, most secrets are quite easily countered with this deck with Kezan Mystic. Especially, Mirror Entity gets wrecked hard with Doomsayer and Explosive Sheep quite often. The only annoying secrets are Counterspell and Redemption, which are not that popular in current meta.
  
  
• Unstable Ghoul: This was actually in the early version of deck. It combos with Explosive Sheep which ultimately deals 3 to all minions which is quite insane board clear in early games. But since BRM launch, Grim Patron punishes this combo so hard, and 3-health minions keep getting out of meta so it is removed from the list.

List of tech cards

• Light of the Naaru and Earthen Ring Farseer for additional heals. You might want to include Auchenai Soulpriest in this case since they may be used as burn spells as well.
  
  
• Second Doomsayer against zoo.
  
  
• Second Holy Fire against midrange.
  
  
• Second Mind Control, second Big Game Hunter and Deathwing against controls.