Hearthpwn

I've been having great success with this on the ladder so far.  Been playing with it and tweaking it the last few days and easily made it to diamond with only a handful of losses, mostly due to RNG or miscounting my own mana trying to learn a new deck.

You will rarely actually complete this quest except vs really slow control decks where your combo cards are in the bottom of your deck.   Completing part 1 is often good enough.  You want discounts on your Mo'arg Artificer, Guild Trader, Il'gynoth cards.   This deck can give lots of mana discounts.  Guild trader is particually good since it keeps any discounts it gets even if you trade it back into your deck or use glide on it.  I've often completed the OTK using only 5 mana dealing 36 damage. (I've done over 100 damage before).   

The tradeable cards help a lot with completing the quest stages.  They are very flexible and help cycle through your deck to get your combo pieces. I'm doing the OTK way earlier way more often than before the patch.  

Jace Darkweaver is great as a board clear/heal/card draw depending on which fel cards you've casted so far.  Very strong late game when you need 1 or 2 more turns to get your combo and discounts.

Fel Barrage is also really strong early game vs aggro and late game to get that extra face damage in.   If they have an empty board or they have 4 hp hiding behind a massive taunt? This card will go face. Add in some spell damage and you can deal a surprising amount of face damage even when you don't have your full combo. 

I'm sure once fully optimized this can be at least a tier 2 deck depending on the meta.