Hearthpwn

1. Introduction

Hello guys! My name is Shadow and I am the creator of an overwhelmingly popular deck called "Warlock F**ker", which is basically a variant of Spiteful Priest to deal specifically with Cubelocks.
I'm talking about this deck: https://www.hearthpwn.com/decks/1017617-warlock-f-ker-budget-dragon-spiteful-priest
This is a much different deck. Unfortunately, I had to remove some cards due to the Wild rotation.
Goodbye Netherspite Historian, Drakonid Operative and Kabal Talonpriest... :(
This deck is still in testing, so I might change a couple minions. Below is a complex guide made to help you. Enjoy! :)

I've reached Rank 5 for the 1st time in my life! And it was with THIS deck! Thank you for your postitive feedback, I appreciate every single comment below in the comments section <3

2. Card choice

• Northshire Cleric - the best 1-drop for Priest. Good stats and our only card draw. Pretty much useless in end-game, so try to get this card on your starting hand
• Acidic Swamp Ooze - a tech card to counter Cubelocks and some other decks like Dudeadin or Tempo Mage.
• Faerie Dragon - good 2-mana drop. It is a Dragon synergy trigger and a good card to combo with Shadow Ascendant. Remember that you can't heal it, though!
• Shadow Ascendant - it's a decent early-game card, included with the purpose of buffing your other minions. Always keep this on your opening hand
• Stonehill Defender + Tar Creeper + Tortollan Shellraiser - these are some good taunt minions, pretty much stopping your opponent from playing aggro. Stonehill Defender is great in each phase of the game
• Duskbreaker - this card is an insanely good AOE with a 3/3 body attached to it. Always keep vs aggro. It's a real game-changer and has got Dragon synergy
• Scaleworm - you might think that it's a pretty weird inclusion, but due to many Dragons in our deck, this Beast is good in dealing with your opponent's creatures
• Spellbreaker - the most important tech card in this deck... It's versatile in dealing with everything: from Taunts to buffed creatures. Use it wisely!
• Twilight Drake + Cobalt Scalebane - both are great Dragons and common inclusions in this type of deck. I don't think that there is much to write about them, their role in pretty obvious for a Spiteful Priest - C O N T R O L!
• Cabal Shadow Priest - it's a card of my preference, you can remove it if you feel like it's useless. Personally, I found it useful dealing with annoying, low-attack minions. Also, it's great to counter Possessed Lackey and slow down your opponent
• Spiteful Summoner - absolutely necessary.. The whole deck is built around this particular minion. Try to draw them before your spells, or you'll be in a baaad position. Play this card when the board is controlled, don't use immidiately vs aggro
• Nightscale Matriarch -  Dude, what are you smoking...?  Don't worry, it's nothing dangerous ;)  You can replace this Dragon with something else - I put this card in my deck because I find it a good control tool in late-game. Also, it has got a Dragon tag
• Psychic Scream - our only guaranteed full boardclear. If you feel like this card isn't good in your match-ups or breaks the Spiteful synegry, feel free to change it to an other minion
• Free From Amber - a great Discover spell and a powerful control tool. This card is obligatory in a Spiteful Priest deck
• Bonemare - even after its nerf, this card's still playable. It's commonly used to buff friendly minions to protect other characters OR to effectively trade/push face. Never keep this on your opening hand
• Mind Control - an amazing spell, its power allows you to steal key minions from your opponent (hello Voidlord!) or move that big Taunt in order to kill the nemy hero. It's a core card in this deck

3. Fighting Cubelock

Okay guys, in this part of my guide, I'd like to describe how to beat Cubelock. Of course, you can't rely 100% only on the tech cards, skill is also required.

Mulligan: There aren't many Zoolocks atm, so it's pretty obvious that your Warlock opponent is a Cubelock. Always keep Acidic Swamp Ooze as it's a great counter to early Skull of the Man'ari (imagine playing this weapon on turn 5 and immidiately get it destroyed). Also, you should keep the Spellbreaker which is amazing in dealing with almost every type of creature: Voidlords, Possessed Lackeys and Carnivorous Cubes don't stand a chance!

I included Cabal Shadow Priest because I find it useful in taking care of enemy Possessed Lackey or any other low-attack minion. Duskbreaker is good for clearing the board of Voidwalkers and other creatures. Psychic Scream can really f**k your enemy when he plays his DK and gets the Demons summoned. In end-game he'll most-likely have no way to draw cards or to recruit these Demons.

Mind Control should be used on Voidlords, Doomguards and Carnivorous Cubes. If you steal a Demon, your opponent won't have a way to resummon it. 

If you want to destroy 1-mana spells like Dark Pact, Dark Possession or Mortal Coil, feel free to swap Nightscale Matriarch for a Skulking Geist. Good luck and have fun!

4. Mulligan and various matchups

• vs Mage - this one's gonna be Aggro (not a big threat) or Elemental Control Mage. Either way, you want to keep Northshire Cleric and Shadow Ascendant. If your enemy is using an aggressive deck, search for Acidic Swamp Ooze (for Aluneth) and Stonehill Defender + Tar Creeper. Psychic Scream can come in handy when dealing with a full-minion board, although I don't recommend keeping in on your starting hand.
• vs Druid - be prepared for a long, control matchup as Hand and Taunt Druid are now a thing. As always, keep Northshire Cleric on your opening hand. Spiteful Summoner is also great, as it's a pure value card (amazing when coined on T5). If it's a Taunt Druid, keep Spellbreaker OR Mind Control for Hadronox. Simply do your best to control the board as the game is gonna last for a long time.
• vs Hunter - Odd Face Hunter / Spell Hunter. There aren't many other Hunter decks atm, so ALWAYS keep Duskbreaker and 1-2 mana drops. Of course, keep your 3-mana Taunts, but not necessarily Tortollan Shellraiser. Pro tip: Trade each single enemy creature. Heal your face very often. Common aggro plays (watch out for them!):

- Eaglehorn Bow + 2x Southsea Deckhand + Hero Power = 10dmg face

- Unleash the Hounds + 2x Kill Command = 10+dmg face

• vs Paladin - Odd Aggro Paladin is now a Tier 1 deck. It's even more dangerous than Face Hunter, because of the constant board fill (Hero Power, Divine Favor). Keep the same cards as vs Hunter (described above). Play like vs every aggro opponent - trade everything, heal your face. Acidic Swamp Ooze is useful in dealing with many weapons - keep in mind that Pala uses like 4-5 of them.
• vs Priest - Expect either a mirror matchup, Combo or Lady in White Priest. All of them are mean a long, control game. Remember to trade each minion, especially vs Combo Priest. They can easily prepare an OTK if you leave a high-health minion untouched. Mulligan is the same like for every control matchup: Northshire Cleric, Shadow Ascendant, Spiteful Summoner, Stonehill Defender, Faerie Dragon (to trigger Dragon synergy).
• vs Shaman - Ohh boy, it's gonna be a tough one. OTK Shaman is now a thing and the only way to win this match is to out-tempo your opponent. Assemble a solid board, trade each card draw minion (Mana Tide Totem, Acolyte of Pain). Spellbreaker can be used to silence Bloodmage Thalnos, Doomsayer or any Taunt minion. Mulligan for cheap minions, Spiteful Summoner is also good. Pro tip: Watch out for Thalnos + Lightning Storm as it can wipe out your whole board. 
• vs Rogue - it should be rather easy. The only Rogue decks working feasibly atm are Kingsbane and Steal Rogue. Mulligan is the same as for other control matchups. Vs Kingsbane Rogue, you want to win ASAP before he upgrades his weapon to 12/3 or so. Spellbreaker is a great counter to Edwin VanCleef, use Acidic Swamp Ooze to destroy his weapon early. Facing Rogue, just use your common sense and you should do well!
• vs Warrior - I have faced many Odd Quest Warriors and they aren't a big threat. Basically, the only thing you need to keep in mind is that they have many removals, so don't get greedy in overflooding the boards with minions. Control, my friend, control.

5. Card substitutions

• Cabal Shadow Priest - You can put in an Obsidian Statue or 2nd Spellbreaker
• Nightscale Matriarch - I included this card in my deck because it's a Dragon. You can put a Primordial Drake instead or 2nd Bonemare (not a Dragon tho)
• Psychic Scream - If you feel like this card destroys your synergy with Spiteful Summoner, swap it with a minion. Skulking Geist is a nice tech card, very helpful vs Cubelock / Kingsbane Rogue / Odd Paladin.
• Free From Amber and Mind Control can't be removed. They are the core of this deck, along with Spiteful Summoner
• Duskbreaker - can't be replaced, it's a key card vs almost every deck
• Zola the Gorgon or Twilight Acolyte are also good substitutions - the first one can be used to generate additional Duskbreakers/Summoners while the second is good in dealing with huge, dangerous enemy minions

Thanks for reading, I'll add more content to this guide if it becomes popular!!

Check out this video of Khristophesaurus using my deck!

Another one! By kiwiinbacon!

Thank you Tommy Wave for a really extensive video!

Thanks a lot All Arounder!  It's the 4th video of my deck already!