Hearthpwn

This is an amazing Demonlock deck I have played with recently! It is super fun and actually pretty successful! I had been running The Demonic Lord - A Competitive Demonlock 1.2 deck (made by lDantonl)  for a while, but I couldn't find success. I watched a bit of Noxious' vids and stumbled upon his video of his Demonlock Deck. I built the deck with what I had, and then added cards to make up for what I didn't want in the deck (namely, the Voidwalkers, Shadow Bolts, and Blingtron 3000). When I queued up and was choosing my starting hand, I realized I still had Shadowflame in my deck from The Demonic Lord deck! I ended up playing the match out and I had a lot of fun! So, I decided instead to just keep the cards I didn't ever intend to have in the deck right where they were! I ended up with an awesome midrange Demonlock deck that didn't run into most of the issues suffered in other demonlock decks (IDantonI discusses how typical demonlock decks run into the issue of bad cards getting Voidcaller'd onto the board instead of a good card like Mal'Ganis). Occasionally you do end up with a Void Terror on the board where you would have preferred a Floating Watcher, but most cards you don't want to get sucked out by Voidcaller are cheap enough to be played with it anyway. Just know when to play your Voidcaller at the right moment! I have to say, I don't intend to sell this deck as competitive or good for climbing the ladder. Right now, I play this deck when I'm interested in having fun! The biggest issue I've encountered is not having something to play early if I don't draw my Flame Imps/Mistress of Pain or they don't play something removable via Darkbomb. We'll see if that calls for more early drops (probably in the 3 mana slot as that is lacking) but so far I'm still having fun. It can still win games, but not at the success of something like Handlock. Now, let's get into the deck!

 Demonlock is a deck type that has always been around. It was inspired by Demonfire's second effect of buffing a friendly demon. Back then, that was about it for Demon-synergy. After Naxxramas brought us Voidcaller, people tried Demonlock again. This time to more success, but still not quite that of a viable deck. Goblins Vs. Gnomes brought us an array of Demon-synergy cards, Mistress of Pain (when used with Demonfire or Demonheart), Imp-losion (when used with Mal'Ganis), Demonheart (when used with any demon), and Mal'Ganis (his +2 +2 for friendly demons effect). Now, we have seen a few Demonlocks running around touting their Demons and Doom. Are they viable yet? Even with all these new Demon-synergy cards, I would have to say no. Am I blind or just unlucky, as I have yet to see more than one on the competitive ladder? Who knows. All I can say is that Handlock and Zoo are still the top decks for Warlock to be seen running. With all that said, why make a Demonlock deck at all? Why bother if they aren't viable? The plain and simple answer to that, would be that they are fun as all hell! It is the deck I turn to when I am tired of the struggling climb up the ladder and just want to have some fun. I can tell you right now, with this deck, you are bound to have some fun. After that mouthful, I hope you guys enjoy the rest of the guide as I go over mulligan strategy, reasoning behind my picks, and other options. Thank's for checking my deck out! Please, share it and leave an upvote! It helps me a lot and gives me the encouragement to improve and make more decks! Enjoy!

This deck is a control deck, but with a suitable early-game. You want to keep Flame Imp, only one Demonfire/Darkbomb, and Mistress of Pain. Situational keeps: You want to keep Hellfire against Hunter, Paladin, Shaman, and Warlock. That is because those classes typically run decks where there will be a good amount of minions on the board come turn 4. Imp-losion can be kept against slower classes that still put things down early game, Paladin, Priest, Rogue, and sometimes Druid. You can keep Mortal Coil against any class that would play a Clockwork Gnome, or if you also have a Mistress of Pain as the two can work together to clear a 2 health minion. Voidcaller can be kept as well, but if you draw into it, it is better. It is much better to throw it back and get Flame Imp/Mistress of Pain to play early instead of the opposite where you keep Voidcaller only to draw those after you play it as they are the worst targets to get sucked out by Voidcaller. In slower matchups where you don't have a 1-2 drop anyway, feel free to keep it. Against hunter, you need to throw it back and look for early removal and minions. Tell me in the comments if there is anything else you would keep in hand and why!

Mortal Coil - This card is pretty strong with all the Clockwork Gnomes running around. Let them know they're not ready with a painless put-down today! This card also helps with those unfavorable trades by adding that one extra damage you needed. I can't recommend running two of these as I don't think there are that many good uses for it in this meta. 

Power Overwhelming - Did you know the short way to say this card is PO, and backwards that makes OP? The card is not OP, but it can have some epic uses with Void Terror and Recombobulator. I'm not running Recombobulator unfortunately, but you can! It also can work well with Voidcaller as it has a weak body for trading and it dying at the end of your turn isn't terrible with Voidcaller's nice Deathrattle. I'm only running one as the deck can't guarantee a minion on the board as well as something like a Zoo deck or an Aggro deck can. 

Flame Imp - Why not? It's a 1 mana 3/2. Yes it is a bad target for Voidcaller, but it has synergy with Floating Watcher. Not to mention, it's only 1 mana! You can just play it with or before Voidcaller to avoid disaster! Turn one Flame Imp into turn 2 Demonfire isn't a bad play either. That takes the deck on a more aggressive turn and can make your opponent fumble. I would only do this on an empty board though or to trade with a 2/3 where I'm left with a 5/2 that demands an answer. 

 Darkbomb - It's like a freeze-less Frostbolt! 2 mana, deal 3. Fair enough. I don't think I really need to explain this card, but I will. It is early game removal to push the game into the mid to late game where you can really start to throw down threats. Simple as that. 

Demonfire - The Demon-synergy begins! Demonfire is a less efficient Darkbomb, but the friendly Demon effect gives it bit more use. It has really good synergy with Mistress of Pain where you turn two Mistress turn three Flame Imp + Demonfire (on the Mistress of Pain) clear whatever they played. It can be used on scary targets with 2 health like Knife Juggler!

Mistress of Pain - Actually while writing the Demonfire info I thought I was writing about the Mistress of Pain and had to cut almost half of what I wrote! It's funny to me. Mistress of Pain is one of the better Demon-synergy cards as it works very well with Flame Imp, Demonfire, and Demonheart. It is a good enough 2 drop and when buffed with Demonfire it can really stop an Aggro deck in their tracks. My only complaint about this card is that early game against control decks you're not really taking damage, so the effect isn't doing much. Late game, where you want the healing, the card is hard to put into play and then attack next turn. At that point you'd rather have a minion that did something beneficial and spent more of your mana. 

Void Terror - I put this guy in the deck as only a one-off because of his synergy with Power Overwhelming, Voidcaller (using the battlecry to trigger the deathrattle of Voidcaller), and Sylvanas Windrunner. I did't want to put two as that would mess up Voidcaller by adding too many bad targets to get called out and two is too many! Just stick with one, you're going to like the results. I guarantee it. 

Hellfire - A very solid AoE removal spell that has great synergy with Imp-losion! I'm kidding. This card has terrible synergy with Imp-losion. But, it is still a great AoE card! You can use it to finish off your Voidcaller to cheat out a big Demon or just swing the game with an epic board clear. A pretty obvious include.

Imp-losion - Why not imps! Why not even more imps!?! Well they are the most annoying of all demons, but they love Mal'Ganis. And you thought Quartermaster was annoying! The card is also really good against Aggro as it can kill a minion and the resulting imps can potentially finish off their other minions. The imps work with Demonfire/Demonheart as well which is always good for stuff and things. I like Imp-losion mostly for the Mal'Ganis synergy. It is pretty fun when you summon all those cackling 3/3s! 

Shadowflame - Now this is one people might be a little confused about. It was actually never intended to be in my deck but when I ended up with it in there, I was happy I had it. It works very well with Power Overwhelming, Demonfire, Demonheart, Voidcaller, sometimes Sylvanas Windrunner, and the Infernals from Lord Jaraxxus's hero power. You'd be surprised how many uses this card has and how amazing it can be sometimes. I absolutely love the card! 

Summoning Portal - This card is super fun! It can let you pump out all your cards, get a turn 7 Mal'Ganis or Lord Jaraxxus, or just die for free. My issue with this card is that it doesn't do anything when it comes out and is weak for tempo. It is definitely a weak link in the deck and could be replaced for a Harvest Golem or some other good 3 drop, as this deck lacks those the most. It is still fun being able to Lord Jaraxxus and then summon an Infernal that same turn. It's not a key card in the deck and can be replaced fairly easily. 

Voidcaller - He is what makes the deck work to its best! Voidcaller lets you cheat out a Mal'Ganis or a Floating Watcher which saves you a lot of mana and gains you a LOT of tempo. This is probably one of, if not, the strongest tempo card in the game. You need to know when to play it at the best time though. You don't always throw it out on turn 4 because you might have a Mistress of Pain or Flame Imp in your hand that needs to be played before the Voidcaller. This card is so much fun and works very well with Power Overwhelming, Void Terror, and Shadowflame. Get callin!

Demonheart - One of the new Demon-synergy cards that is pretty cool! It is strictly worse than Fireball, until you hit a friendly Demon. This card is sooo good with Mistress of Pain, even when you're full health. A 6/8 is a pain to deal with and it will keep you at full health indefinitely. It also works with Imps summoned by Imp-losion, so you can sneak in a strong minion through your 1/1s! I wouldn't run 2 ever as it is a poor removal option and Mistress of Pain is really the best target. It is an awesome card though! 

Faceless Manipulator - There are a number of big scary cards in this deck: Floating Watcher, Mogor the Ogre, Sylvanas Windrunner, and Mal'Ganis. These are all great targets to copy! Especially Mal'Ganis, as the +2+2 to friendly Demons stacks. With this many cool cards to copy you gotta put in a Faceless Manipulator! Only 400 dust if you call now!

Floating Watcher - He floats and he watches, and he gets very powerful, very quickly. Combined with your Life Tap, Flame Imp battlecry, Dread Infernal battlecry, and even Hellfire he gets huge! He is especially good when you can call him out through Voidcaller because you can get him snowballing really quickly. He is one of my favorite cards in GvG and I think it was a little odd they made him a common card instead of rare. 

Siphon Soul - Destroy a minion, and restore 3 health to your hero. Not bad at all. A great card against control that helps you tip the boar control back to your favor. I don't see a reason not to run at least one of these bad boys.

Dread Infernal - A nice big 6/6 with the occasionally nice Whirlwind. It works well with Voidcaller and Floating Watcher. Its that nice strong card you parents keep telling you to bring home. My parents are weird. 

Mogor the Ogre - MOGOR KILL! He's really just in there for fun and could easily be replaced to bring the curve down. Sometimes, he can save your ass with his hilarious effect. Other times, you can just end up messing yourself up with it. Definitely a card that is fun if you're looking for it! 

Sylvanas Windrunner - Another card I didn't plan on running in the deck, but she actually worked out really well. She has synergy with Power Overwhelming, Void Terror, and Shadowflame. She's also a great target for Faceless Manipulator. She is one of my favorite legendaries and always will be <3

Lord Jaraxxus - You face Jaraxxus! Eredar Lord of the Burning Legion! He is the lord of this deck, truly. He is a fantastic legendary that in long games, against Control Warrior or Priest, can end the game with a couple of 6/6 Infernals. He isn't a terrible Voidcaller target either, as 3/15's are pretty strong last time I checked. Especially with a Demonfire or two. 

Mal'Ganis - Did you know Mal'Ganis is Mal'Ganis? And that he is eternal? He told me himself. He is an amazing legendary that I've had so much fun with. He is the best target for Voidcaller (most of the time) and has fantastic synergy with Imp-losion. The Demon buff effect is super nice, but being immune is even better. You can play all the Flame Imps, Dread Infernals, and Life Tap all you want! When I unpacked this guy it was amazing. He is one of my favorite legendaries and probably my favorite from GvG. 

I hope you respect my opinion on all the cards listed here, If you have more reasoning behind a card or two feel free to add it in the comments below. I always appreciate feedback! 

Give me suggestions on what else should be here! I love to hear it! 

Doomguard - This is a great card no doubt, but not in this deck. It might seem like it with Voidcaller negating it's battlecry, but that doesn't always happen. There are better targets then Doomguard already, so there is no need to run it. You can't really risk throwing out Mal'Ganis, Sylvanas, or Lord Jaraxxus through his battlecry. We wouldn't dare summon him in this deck! 

Loatheb - He's a great replacement for Mogor the Ogre if you want to get a bit more serious. Go ahead and swap the two if you want to play it more on the ladder.