Hearthpwn

Credits to M0ti0nz as this deck was made based on his version of Demonlock

Currently studying for my finals so I'll slowly work on this :P

Card choices:

Power Overwhelming : Has a very low cost for what it does. I chose it over Demonheart because as others have said, Demonheart can be replaced by Power Overwhelming to trigger Sylvanas Windrunner on turn 7 or can be used to power up any minion for a low cost when you need 4 damage for game or to turn a small minion into a great Shadowflame target.

Voidwalker : Voidwalker's very good to defend your important minions and is a great turn 1 drop to kill 1HP minions, but I felt 2 of them is a bit too much as you wouldn't want to draw a second one over any other card.

Darkbomb: Warlock's new staple removal due to the Soulfire nerf. It is basically a Frostbolt without the freezing effect and can take care of most minions early game. It can also be used to finish off a stronger minion that has taken damage.

Demonfire: Very strong card that can be used on any of the 10 demons in this deck. It can also be used as a removal tool early game if you're in a pinch. However, I'd save it to buff your Mistress of Pain or Voidwalker. It can also be used in the same fashion as Power Overwhelming to give you the 2 damage needed to win or to Shadowflame.

Ironbeak Owl: This deck desperately needs a silence for all the annoying deathrattles or whatever there is in this new meta. Since we only play a single Siphon Soul, we need something else to get rid of taunts, Tirion, Sylvanas, et caetera. It can very well be the difference maker between a win or a loss, so always save it for the right moment (e.g. don't use it on a minion that has not been buffed or that you can clear without losing too many cards).

Mistress of Pain: This card has been called the Armorsmith of Warlocks and it is true. Whenever it deals damage (even when it gets hit by an enemy minion), it heals you back for the damage it's done. Buff it with Demonfire and you get healed for 3HP each time it hits something. Even when it is not buffed, you can use it to kill 1HP minions while drawing for only 1HP each turn.

Earthen Ring Farseer: Staple healing card for Warlocks. Solid 3 mana drop.

Hellfire: Best AoE removal card against aggro-type decks. Can also be used to trigger a low-HP Voidcaller or Sylvanas. It can also trigger the effect of Floating Watcher.

Imp-losion: I was skeptical at first. However, the imps summoned can be buffed by Demonfire and Mal'Ganis. It can kill an enemy minion while providing some for you which can be traded for more minions.

Shadowflame: Great AoE removal tool. It has great synergy with Molten Giants and Power Overwhelming. It can be used to trigger Voidcaller. However, since you need to have a minion on board to use it, I wouldn't play 2 copy of these as we want to keep our minions alive.

Defender of Argus: Great card to use to buff your minions and use them as meat shields mid to late game. It is best used with any big minion. However, you can also use it on Mistress of Pain forcing your opponent to heal you while they lose minions.

Voidcaller: The best card in the deck. It is a win condition and always keep ONE copy when you mulligan. You don't want 2 of them in your starting hand as the first one can drop the other one.

Floating Watcher: The 4/4 body is pretty weak for the 5 mana cost. However, it is best when played on turn 7 preceding Life Tap, buffing it to 6/6. If not dealt with immediately, it grows exponentially strong. Also, it can be summoned for no cost via Voidcaller.

Loatheb: I chose it over Troggzor the Earthinator since it stops you opponent from using spells for one turn. Your best bet is to use it right after you summon a big minion via Voidcaller to keep it alive for one more turn. When playing against a mage it is also a good idea to keep it in your starting hand so you can time exactly when you want to use it.

Sludge Belcher: The card most of your opponents do not want to see when they're trying to kill you. It is an amazing meat shield. It can also be used to bait out Hex, Earth Shock, Polymorph or other silences so your bigger threats remain safe.

Siphon Soul: This card can get rid of absolutely any minion. However, I only play one copy because of its high mana cost and the abundance of aggro decks.

Dread Infernal: Who thought the 1 damage nuke might come in handy? It can be used to finish off damaged minions on the board or summoned via Voidcaller for a nice surprise. It was chosen over Doomguard mainly because you don't have to discard 2 valuable cards to summon him.

Sylvanas Windrunner: A nice card that you can use to steal any minion you want from your opponent. It combos perfectly with Power Overwhelming and Shadowflame. On turn 7, if your opponent has a single big minion, you can use Power Overwhelming on her to steal it at the end of your turn. On turn 10, combined with Shadowflame, it can clear the board and steal the remaining minion. Usually it's a pretty big one.

Lord Jaraxxus: Your savior. It saves you from death late game while summoning 6/6 Infernals for 2 mana. When it is dropped by Voidcaller, it becomes a 3/15 body which can be used to hit minions or become a 4/16 meat shield when buffed by Argus.

Mal'Ganis: The second savior after Jaraxxus. When dropped by Voidcaller, it's bound to change the course of the game as the opponent will have to focus their resources on this card. It hits very hard but also makes your hero immune. With a taunted minion by its side, it is your best weapon. Also, do not hesitate to play it by itself when you're in trouble. It can delay your death and give you one more turn to answer your opponent.

Molten Giant: As a handlock player, I cannot imagine not playing this card in any Warlock deck. They give you late game momentum and can be played for 0 mana into a Shadowflame or Defender of Argus punishing your opponents when they push too much. It also has great synergy with your Hero Power.

 

General Mulligan tips;

-Keep a Voidcaller and a Mistress of Pain

-Keep one Darkbomb for early game removal

-When you're sure to play against aggro, keep a Hellfire, it can't hurt.

-Always mulligan any other demons than those 2 I mentioned, you can draw them later.

-Keep a Farseer if you're sure to take damage early on

-Loatheb is close to a must against mages, otherwise mulligan it

-Never keep; Moltens, Siphon Soul, Sylvanas, Argus

-Belchers are very situational, keep one if you can't find proper removal and you're playing against aggro.