Hearthpwn

After trying a few other classes and getting Twisting Nethered to death, I arrived on this deck.   I've gone 5/5 with it so far, and I figured the deck is good enough to publish as no games were even close.

Fighting The Crone

The Crone will focus Dorothee and ignore both you and many minions on the left (charge) side of Dorothee.  She will often make bad trades with taunts, but I've noticed that she is generally hesitant to kill a mad scientist.  I've had a taunted scientist facing multiple 3/4s and she has passed her turn rather than kill it.   The most important element of this fight is that she will cast Twisting Nether on turn 8 and immediately use her hero power to kill you.  That means you need to kill her before turn 8 or stop the twisting nether.  This deck can do both.

Strategy

Your goal is to give a minimal level of protection to Dorothee while burning down the witch as fast as possible.  To that end you will generally want a single taunt minion played to Dorothee's right while all additional minions go on her left and charge immediately.  Use your spells and Flamewalker triggers to keep her board clear.  This has the added bonus of the AI casting buff spells on your minions.  I've had a 9/8 divine shielded Mad Scientist because she's thrown so many random buffs out.

The Cards

Counterspell - This is your answer to Twisting Nether.  In every game that I've gotten to turn 8 she has cast Twisting Nether.  I assume she starts the game with it, or I have awful luck.  In any case, her deck is filled with spells so if Counterspell is in your hand, hold it until turn 7.  On turn 8 she will cast Twisting Nether right into it. She does have at least two Twisting Nethers, so be prepared with a plan for a second if you can’t close by turn 9.

Loatheb - Loatheb is a buffer in this match.  If you don't have a Counterspell in hand, hold him until you do.  You can cast him on turn 7 to buy one additional turn.   You can also get up to a lot of shenanigans with Loatheb Duplicate and Echo.  I've had a game where I ended up playing a Loatheb every turn from 5 to 10.

Flamewaker and Mana Wyrm - These are your main workhorses.  In the average match your opponent would kill them before they got out of control.  Since the Crone is focused on Dorothee she'll let you sit them on the left and do damage for days.  If you have Duplicate up, throwing a flamewaker or wyrm on the taunt side is a reasonable play.

Mad Scientist - This is your alternate plan for counterspell.  If I get him early, I like to throw him on the taunt side and take what I get (preferably duplicate).  If I get him later I usually put him on the charge side and trade him on turn 7 or kill him myself to get a shot at a counterspell.

Sorcerer's Apprentice - She generally goes on the left unless you really need a taunt.  She's in here for burst turns with Firewakers and generally speeding up your play.

Polymorph - These are a counter to Abominations which kill most of your small minions.

Ethereal Conjurer - Gives you a shot at a really good spell, any spell will still do work for your Wyrms and Flamewakers and he charges for 6.  If you play him on Turn 5 he can get 24 damage in by himself before the Crone can cast Twisting Nether.

Substitutions and Other Options

I'm generally happy with this deck in terms of cost as the only legendary is from an adventure.  But, here are some other things I've played around with.

Ice Block/Echo of Medivh - This is an additional survival package that you can run.  You can duplicate Dorothee with Echo, put down an Ice Block and then weather one use of the Crone's hero power before replaying your new Dorothee.  I'm not crazy about this combo because Ice Block is only relevant in this match if you get hit by the Crone's hero power whereas your other secrets are always going to provide some utility. 

Echo of Medivh --> Fireball - I only have 1 Echo, but I would try playing a second if you have it over the fireball.  Getting a couple extra wyrms and/or firewakers can be huge.  Fireball is fine though.

Kirin Tor Mage - Dropping him on turn 3 to swing for 4 and play a secret is a reasonable play.  If you want to go the Ice Block path, I would consider finding a place for him.

No Loatheb? - I'd consider another Echo of Medivh, Faceless Summoner, another Fireball, or the Ice Block plan.

Mulligans
Toss back anything over 3 mana.  You can make most anything else work.  Ideally you want a T2 minion and a T3 Flamewaker.  T1 Mana Wyrm is bonus.