Hearthpwn

Hey, i made a reddit post a couple of days ago after i reached Legend with this deck: https://www.reddit.com/r/hearthstone/comments/5kepk8/got_legend_with_self_brewd_demon_warlock_deck/

And since a lot of you guys asked for it, i decided to make a quick guide about it with strategy and mulligan options and matchups. So...let's get started:

Strategy and Mulligan:

The goal is to set up an early lead with 1 drop demons and try to combo them with your buff cards or discard mechanics (with malchezar's imp and tiny knight of evil) and get a snowball going by outpacing and out tempoing your opponent with bigger and bigger demons.

As for mulligan, there are a lot of different options here but you almost always want to get early board presence with the amount of 1 drop demons you have. Keep as much of them as you can early on to ensure that at least one of your demons stick by turn 2 or 3 so you can buff them with demonfire or bloodfury potion. You should consider keeping any discardble card you can find as well (Golems and/or Fist of Jarraxus) because you'll eventually discard them and get a lead that way.

Matchups:

Shaman - look for soulfire to counter totem golem or 1 drop demon + bloofury potion if you have the coin. it totally screws them up because most likely they'r going to totem up the following turn leaving you with an opening to snowball from there. Always be aware of lightning storm and malestorm portal (Crystalweaver is key in this)

Warrior - keep soulfire and any discardble cards you can get your hands on. several 1 drops early is a good way to get them to trade instead of them mindlessly smorc you. A buffed voidwalker wins you the game almost automatically (keeping demonfire for the buccaneer isn't a bad idea either)

Druid - curve out and you should be fine. Innervate is your worst enemy. Try to apply a lot of pressure early so that they have to spend all their mana on removal and don't develop the board.

Card Choice:

Pitlord: The million dollar question, "why the fuck would you pic Pitlord over anything else?" Well, being a warlock fan-boy, i've experimented a lot and did a lot of testing with every single warlock card to see what could make the cut. Pitlord caught me by surprise, as it did many of you, but the more i thought about it, the more it made sense. The reason behind it was because of the whole concept of demons: you put big minions ahead of their curve but with some kind of trade-off, either by discarding or taking a chunk out of your life total. I think that's the logic behind the hearthstone dev team and why they made demons the way they are. Pitlord is a fantastic minion (stat wise) for only 4 mana. The trade off being that you pay 5 health to play it. But it's totally worth it. The deck revolves around playing early minions, like flame imp, void walker, malchezar's imp, succubus (at some extent), imp gang boss and then buffing them up with demonfire and bloodfury potion. Meaning, you get a lead early and you snowball the game after that so that your opponent can't react to anything you do while you push your way to victory. Pitlord comes as a tempo play against your opponent. On turn 3/4 they are preparing to deal with your board but then you drop this huge-ass demon on the board. Take a mage for example...on turn 4, they either frostbold-ping-trade against your board, or they have to deal with your Pitlord and fireball it, leaving your board intact to get buffed the next turn (or you play a doomguard and they have to fireball+ping/polymorph, wich they already used on your Pitlord and don't have the mana to do so)

Replacements:

Darkshire Counsilman

Felguard

Demonwrath

Note: Updating the guide whenever i have a spare time! Thanks for all the replies :)