Hearthpwn

This is the list I used to get to Legend in about 100 games or so. Currently sitting at like top 2k, with a 80% win rate. Haven't had a chance to play that many games to push for top 100.

- Altruis the Outcast is your most sought after card, never mulligan it away even if you want to use it pretty late, depending on the match-up. I consider it by far to be the key win condition that can completely turn the tempo in your favor. Against something like a spell druid, it is an absolute god-like card. Without it, you probably can't win if you don't get an insane early curve.

- Think ahead, planning your outcasts and tempo plays is really, really crucial. Mana Burn can be an annoyance in that regard but honestly, I consider it to be a rather weak card, so don't worry about it too much. Whenever you can outcast a card like Spectral Sight or Crimson Sigil Runner, go for it, especially if you're yet to draw Altruis the Outcast or Skull of Gul'dan.

- Speaking of Mana Burn, I used to run this card and sometimes it can be quite good when played before turn 6 during a mirror match or when you play it twice on turn 3 with a powerful early board after a perfect curve. Preventing those mid game board clears can also be quite good. The thing is, there are times when it does literally nothing.  I am torn on it honestly but I feel like having a 1 mana drop that actually does something is way better. 

- In some matchups, you can use Altruis the Outcast pretty early on after triggering the first Skull of Gul'dan. Generally speaking, you don't want to use the card before round 6 and before using Skull of Gul'dan.

- In mirror matches, Altruis the Outcast should be used with care, if you have him in hand do NOT be tempted to play him early on, you want to save him for when you're really behind to turn the game around and push for that lethal. If you determine that the Demon Hunter you're playing against is not a combo deck, even if you're at 10 health or so, you're rather safe (assuming the opposing Altruis was played) since aggro decks can't afford to run Inner Demon. The rule of thumb against other aggro/tempo Demon Hunters is as follows: use your Altruis the Outcast AFTER your opponent uses his.

- Using Kayn Sunfury just as a 4 drop on curve against other aggro decks is completely fine, sometimes you even want to play him against control decks when there are no taunt minions on the board simply to prepare for outcast triggers with Altruis the Outcast.

- Galakrond Warlock is one of the toughest matchups in the current meta, if he gets the right cards, you can't really win. Remember about his 5 mana board clear that swings the tempo in his favor by also placing a 5/5 drop on the board (referring to the Crazed Netherwing). Try to play around it. You have 2 possible ways to win: if you get a good mana curve early, you can try to push for lethal but if he gets all his removals, you are guaranteed to lose. The 2nd approach is to play a reserved tempo match, getting damage when you can but also saving those twin slices/the coin for Altruis the Outcast/Questing Adventurer Combo. Try to play the big Questing Adventurer with other minions so it can't be removed as easily. NEVER play a big Adventurer if the warlock has more minions on the board, he'll just play Plague of Flames. 

- I am using Guardian Augmerchant instead of Blazing Battlemage because that 1 damage is key for finishing off threats that can clear your board while at the same time the divine shield can be used to protect crucial drops such as Battlefiend, Questing Adventurer and Altruis the Outcast. Guardian Augmerchant is especially good against priest matchups and completely counters their early removal cards.

- I used to run Maiev Shadowsong in this deck but from experience I found her to be too slow, she is really good against some matchups tho. 

- In theory, Metamorphosis is a really, really good card and it truly is if you draw it at a right time but drawing it in the opening hand can be really annoying. Honestly, I was considering getting rid of it at times because of how much outcast tempo it cost me during the game's opening turns. Anyhow, always mulligan it away, the card is more of a finisher similar to HoF Leeroy Jenkins. 

- If you draw Skull of Gul'dan in your opening hand, generally speaking, you don't want to mulligan it, unless you drew other high-cost cards. If Skull is your left-most card in the opening hand or the other cards to the left of it are 1/2 drops, keep it to get that turn 6 value. Also, be sure to clear threats and have board control in order to be able to play the skull on turn 6.

- If you're facing a lot of mirror matches or other aggro decks, Aldrachi Warblades are a good alternative to Warglaives of Azzinoth/Umberwing. Keep in mind tho, after the nerf the card is extremely weak against control decks - you don't really care about your health since with the intense card draw you'll be the one with more steam, trying to control the game and winning it before running out of cards. Also, you want at least one Umberwing in your deck since it synergizes really well with Satyr Overseer, allowing for an amazing tempo play on turn 3, as a follow up to turn 2 (otherwise, you have to use your Satyr Overseer with a coin and a hero power on round 3, assuming you get the coin that is).