Hearthpwn

Reasons to try this deck: Have you ever killed a Darkglare/Quest Warlock on turn 3? 

Proof Legend 

Found this decklist from Clark HELLSCREAM who made a great video guide (see below). Original list from Goku who played it #2 legend. 

Intro: Due to the The Demon Seed, control and Reno decks are officially dead in wild. Control and Reno decks usually destroy hyper aggro, so them being gone allows Aggro Priest archetype to work.

Playstyle: Plays similar to any other aggro deck (Odd DH, Even Hunter, etc.). If you are familiar with this playstyle you should do fine. Most of your games will be over by turns 5 to 7. I I highly recommend watching the great video above to see what typical plays with this deck look like. 

Pirate Package:
Build a wide board with the pirate package (Ship's Cannon, Parachute Brigand, Patches the Pirate, Southsea Deckhand, Bloodsail Corsair). These cards are fairly weak on their own, but after you drop a Voidtouched Attendant they hit hard. 

Mana Cheating Package: 
Frenzied Felwing: Becomes free after a Mind Blast or any other damage (easy with this deck)
Patches the Pirate: Free when you drop a pirate, good synergy with Ship's Cannon
Parachute Brigand: Free when you drop a pirate, good synergy with Ship's Cannon

Tech Package:
Mindrender Illucia: Use it as follows:
1) Like Loatheb. If you have minions on the board and an empty/near empty hand, you summon Mindrender Illucia, your opponent gets an empty/useless hand, and suddenly your opponent can no longer clear your board. Gives you another turn to hit face, which is all you need to win
2) Vs. Mozaki Mage, APM, Ignite, etc. Steal Ancient Mysteries and/or Ice Block. Steal Stargazer Luna, Conjure Mana Biscuit, Mana Biscuit, dump their damage spells, etc. Any of these and you win.
3) Can play on turn 5 to block a turn 6 Reno Jackson

Mindrender Illucia in action:
vs. Reno Shaman: My turn 5 Mindrender gives opponent empty hand and blocks his turn 6 Reno. I have lethal next turn. He concedes 

vs. Pirate/Quest Warrior. I had board advantage but not much in hand, Mindrender Illucia steals Sword Eater. I get a taunt body + weapon to hit face with. Turn 6 win. 

Kezan Mystic Combo mages run Ice Block and are prolific on the ladder right now. If you steal an Ice Block, it is usually an auto win. Also great for stealing secrets from Secret Mage and Quest Hunter. If you aren't running into any secrets, then you can swap for Tour Guide, Cult Neophyte, Shadowed Spirit, or Knife Vendor.

Kezan Mystic in action: Steals the Ice Block and the game. Turn 5 win vs. Mozaki Mage

Stealing Secret and Tempo from Quest Hunter. Won 3 turns later. 

Shadow Package :

Use your hero power to build your board while denying opponent board, or for face damage.

Voidtouched Attendant: MVP of the deck. Use it to amplify damage of your board. Generally don't want to summon this unless you are getting value from it (I.E, before dealing damage from multiple sources). Can sometimes play turn 1 if you know it'll survive to turn 2 and give you value (I.E., amplfying Quest Warlock self harm)

Mind Blast: 5 Face damage. Good finisher. Easy to cast 3 or 4 times. Bypasses taunt. Synergy with Frenzied Felwing

Shadow Visions: Gives you a COPY of Mind Blast

Example: 4 Copies of Mind Blast. Quest Hunter gets wrecked 

Thrive in the Shadows: To get Mind Blast or Raise Dead. Generally you want to use Shadow Visions first so you get copies of Mind Blast, as if there are none left in deck then you won't get Mind Blast as an option with Shadow Visions. 

Raise Dead: Use it to get more pirates for Ship's Cannon, or to get more Shadowbomber to finish them. 

Shadowbomber: 3 damage to face. Bypasses taunt. 

Twilight Deceptor: Much needed card draw on a decent body. 

Shadowcloth Needle: Extra damage vs. all, and extra board clear vs. other aggro decks. Great vs. Odd Paladin, Murloc Shaman, Pirate Warrior, etc. 

Darkbishop Benedictus: Makes the whole deck possible but sucks as a draw. 

Mulligans:
Always keep: Parachute Brigand, Voidtouched Attendant, Ship's Cannon. 
Vs. Druid, Paladin, Warlock, Warrior: Can also keep Shadowcloth Needle. 
Vs. Mage: Can keep Mindrender Illucia or Kezan Mystic if you know it's going to be Mozaki/APM/combo (90% of them are right now). Stealing an Ice Block or dumping combo pieces= You Win

Matchups: 
Darkglare, Darkglare/Quest: You are favored, they do too much self-damage to survive long. Some lists are very anti-aggro now (Armor Vendor, Defile, Mistress of Mixtures etc.). vs. these you may lose (50/50)
Cute Warlock: You can usually outraced them/are favored. 
Mozaki, APM, Ignite, Miracle Mage, etc: You are favored. Kezan Mystic will win you these games. Even if you don't draw Kezan Mystic, Mindrender Illucia at the right time can steal an Ice Block or dump their combo pieces. Miserable match up for them. 
Secret Mage: You are favored/can out race them. Kezan Mystic helps here, as does Mindrender Illucia when you are out of ammo. Rigged Faire Game won't trigger vs your deck
Handbuff Pally: You are favored/they are too slow usually. Mindrender Illucia when you are out of ammo and steal their big charges :) 
Even Hunter: You are favored/faster. Use hero power to help hold board while minions hit face. Kezan Mystic helps in this one since they run Explosive Trap
Odd DH: Same as even hunter minus the secrets. Hero power to help hold board turns 1/2, then switch to hitting face and race them down. Fairly even matchup. 
Aggro Paladin/Odd Paladin: You are generally faster at racing these decks. Also Shadowcloth Needle helps a lot here. 
Pirate Warrior: Hard/they are favored. Quest pirate is easier to beat than pure pirate with Skybarge, quest slows them down enough that you can out race. Bloodsail Corsair is great here vs. Ancharrr which they get from part 1 of quest. 
Murloc Shaman: They are favored. Sticky minions/your hero power can't keep board clear. 
Quest Hunter: Even matchup unless they draw all their minion removal early in which case you lose. 

More proof of concept:

Turn 3 win vs. Darkglare/Quest

Turn 5 win vs. Darkglare

Turn 3 win vs. Darkglare/Quest 

Turn 3 vs. Warlock 

Turn 5 vs. Darkglare/Quest 

Turn 5 win vs. Darkglare/Quest 

 Turn 5 vs. Darkglare/Quest

Turn 4 win vs. Darkglare 

Turn 6 vs. Darkglare/Quest 

Turn 9 win vs. Secret Mage 

Turn 6 win vs. Secret Mage 

Turn 5 vs. Quest Hunter 

Turn 7 vs. Quest Hunter 

Turn 8 win vs. Quest Hunter 

 Turn 7 vs. Quest Hunter 

Turn 6 vs. Odd DH 

Turn 4 vs. Quest Druid 

Turn 4 win vs. Aggro Paladin 

 Turn 3 win vs. Aggro Paladin 

Turn 6 vs. Aggro Paladin 

Turn 8 vs. Aggro Paladin 

Turn 6 win vs. Pirate/Quest Warrior 

 Turn 5 win vs. Big Priest 

Turn 6 win vs. Kingsbane 

Turn 6 win vs. Face Hunter 

Turn 6 win vs. Pillager Rogue (Cloak of Shadows can't dodge Mind Blast)