Hearthpwn

This version of mill rogue is early-game focused as this deck performs very well against aggro anyway. You will often waste a ton of mana against passive plays and that's okay. Aggro rarely runs out of steam in this meta so I've replaced cards such as N'Zoth, the Corruptor and Sludge Belcher with tempo and delay cards like Counterfeit Coin and Evasion

 I have a 60% winrate with this deck, which is not amazing, but at least it's majority. 

It is a very difficult deck to play, but it can be played competitively, although with a mildly unfavourable matchup against aggro. It is hard countered by Dead Man's Hand, Archbishop Benedictus, and Jade Idol when shuffled smartly, but these cards aren't too prevalent in the metagame. Mill Rogue is not for the faint of heart. Don't craft this deck unless you have most of the cards or are really into mill rogue. 

Gameplan: Delay your opponent from doing face damage with the above tools. Preserve Coldlight Oracles with Shadowstep, Vanish, and Gang Up. Draw lots of cards with it, use up your gang ups on oracles, and then mill all the cards. Try to throw away cards to avoid milling Gang Up. Count fatigue damage and KO your opponent as soon as you can. Use this calculator if you wish. 

Mulligan:

Always keep: Coldlight Oracle

Against all classes except Priest and Warlock: Keep Doomsayers. If you have a doomsayer already, keep a 3-drop taunt. If you have a coin, keep Elven Minstrel.

Against paladin, hunter, and druid: Keep Backstab.

Against Priest and Warlock: Keep The Curator. If you have a coldlight/curator, keep Gang Up, and Shadowstep. With no coldlight/curator, keep Elven Minstrel.

 

Anti-aggro tools: 

(Turn 2):

Doomsayer: Can be used to simply delay a turn, save health, or to kill off a bunch of things behind a taunt. We have a significantly higher chance of winning against an aggro deck if this activates in the early-game.

Turn 3:

Lone Champion, Tar Creeper, and Deathlord.

Removal:

Backstab, Sap

Clears:

Wild Pyromancer: A poor man's Defile, but can function in many ways, and pairs especially nicely with Counterfeit Coin, and Backstab.

Abomination: Helps combat large boards.

Vanish: Note that cards are returned to their hand in the order they were summoned. Once their hand is full, those minions will then be destroyed and their deathrattles will trigger.

Delays:

Doomsayer, Vanish, Valeera the Hollow, and Evasion

For example, a great mid-game usage of Doomsayer is to Vanish the board and then play one, or play one behind a hefty taunt. Evasion on the other hand should be preserved for when you expect to take a lot of damage.

Cards to potentially swap out:

Wild Pyromancer, Counterfeit Coin, Tar Creeper, Lone Champion, Abomination, The Curator.

I think it's pretty good as is. But I've been experimenting a lot with what works.

 

Notable omissions / cards to try:

Mistress of Mixtures - a great 1-drop.

SI:7 Agent - An excellent card, but I think the taunts save more health as long as Backstab is used on opposing Knife Jugglers.

Antique Healbot - replaced now by Evasion, the healbot simply costs too much to be more useful against aggro most of the time. Brann is much better used to mill the opponent's cards.

Sudden Betrayal - A decent card in the early-game against aggro.

Unstable Ghoul / Fan of Knives - okay AoE, which can be especially helpful against aggro Paladin and Hunter.

Eviscerate - a less conditional, more powerful and more expensive Backstab. 

Kingsbane - could possibly work with Deadly Poison, but life total is a concern. 

Edwin VanCleef / Arcane Giant - aim is to mill, not burst. Either of these cards are unlikely to save much health, and we almost never threaten lethal from attacking. 

Sherazin, Corpse Flower - no taunt :(

Vilespine Slayer - a strong single target removal with a body, but sap should do the trick usually. 

Shadowblade - too many taunts are ran in aggro for this to be viable. 2-4 copies of Gang Up should be more than enough to avoid fatiguing yourself to death. 

Fal'dorei Strider - good when you've already won. Can screw up your hand with Leyline Spiders, potentially milling your key cards such as Gang Up or Coldlight Oracle. Can also delay fatigue damage if overdrawing, but that shouldn't be a concern. 

Cheat Death: We'd often be using it as a 2 mana shadowstep. Shadowstep is a vital card though. Cheat Death is decent on Deathlord as well. It's perhaps worth trying out - kind've like a 0-mana Simulacrum. I currently run five 3-drop taunts, and it seems most important to draw at least one of these than to gain a copy when having cheat death.

N'Zoth, the Corruptor - A strong lategame delayer. This deck is more early-game focused and doesn't run Sludge Belcher, but a n'zoth build would certainly be strong too.

Poisoned Blade - the ultimate card, I don't know why I don't use this. 

 

Some statistics for you (if hard mulliganing):

With 2 Coldlight Oracles, you have a 68%/74% (first/second) chance of drawing a coldlight oracle by turn 8 (19/18 cards left in deck).

With 2 oracles and The Curator, you have an 83%/87% chance of drawing one by turn 8. 

With 2 oracles and 2 Elven Minstrels, you have a 91%/94% chance of drawing one by turn 8. Elven minstrels are not guaranteed to get you coldlight, however. But they are cheaper and can be shadowstepped/vanished.

You are pretty likely to lose even against control if you don't draw a coldlight eventually. I'm not quite sure what is optimal. Prince Valanar is an excellent 4-drop if we omit the minstrels,

[Statistics were done as such: 28/30*27/29*26/28, etc. as the chance to NOT draw a needed card. I'm not entirely certain that that's how statistics work, but that's what I remember from high school math.]

 

 Matchups:

Mage: Secret / Aggro mage is our worst matchup. If they use Aluneth we have a chance, but we almost always lose otherwise. We do well against Combo/Quest Mages though. It might be worth forfeiting against aggro mage and instead hard mulliganing for Coldlight / Minstrel / Curator.

Warrior: Pirate Warrior is another poor matchup. Control Warriors might have a Dead Man's Hand, so preserve Gang Ups for when you can double it with Shadow Reflection. If they have 2 and you don't manage to mill one, then you've lost and can concede.

Druid: Token - decent matchup, as vanish ruins their buffs and their mana if they use Living Mana. Against Jade Druid do everything in your power to mill their Jade Idols. It's also possible to win by getting them to few cards in their deck, and then making them draw ~12+ cards in one turn with Brann Bronzebeard + Coldlight Oracles. It feels like a hopeless matchup because of Jade Idol, but you'll actually win a lot.

Warlock: Zoo is a decent matchup. Handlock/cubelock is highly favoured for us, but tricky. [cardMal'ganis[/card] prevents damage, so a Sap should be saved for the end to fatigue them. It is possible to lose from a zany Doomguard combo or a Mal'Ganis poorly dealt with. 

Priest: Highly favoured. Beware using Deathlord against Big Priest and be sure to save an evasion against Shadowreaper Anduin. Try to keep the board clear / have taunts against Inner Fire Priest.

Hunter: Unfavourable.

Paladin: Aggro - manageable. Call to Arms, Divine Favor, and Solemn Vigil all thin their deck, while we have many anti-aggro tools including just the dagger for picking off 1/1s. Against Buffadin be sure to use your Sap and Vanish cards wisely. Be cautious of Sunkeeper Tarim.

Rogue: Mirror match - preserve your Gang Ups when you can double them. Mill does well against Kingsbane rogue.

Shaman: They are often pretty passive in trying to cheapen their Thing from Belows, so it's favourable.