Hearthpwn

This deck is really fun to play as it's a midrange deck that combines elements of curvestone, with great value cards and even OTK potential using the quest reward.

General deck notes and play strategy.

The deck has only 7 spells, but can generate a LOT more with spell generators.  In addition to the 7 in the deck, you can generate up to 13 more spells (assuming you don't let it ride with glyph in which you can get even more).

In addition to the big value you get with the card draw and spell generators the playstyle is kinda like a curvestone dragon priest or a zoo deck.  Simply spam creatures early to get control of the board and then aim to out-value your opponent in the mid to late game with your spell generators.

A note on some of the cards:

Book of Specters:  This card generates great value and often yields 2-3 cards since there are so few spells in the deck (remember the quest starts in your opening hand).  Superior to AI in this deck so it replaces that card.

Lesser Ruby Spellstone:  You won't have any issue upgrading this thing and late game it's a nice value add in any control matchup.

Mana Wyrm:  Seems weird to run this card in a deck with only 7 spells, but you can generate so many more it's easily worth it.  At worst it's a dire mole, but it's almost always better than that.   Great against aggro decks or even late game if you can chain a bunch of spells after playing it.

Leyline Manipulator: This card is critical in letting you dump your hand in the mid-game against faster decks.   It reduces mana from any generated card including flame elementals, pyros upgrades and of course your spells.  You can leverage him for a big swing turn mid-game to help you take over the board or push through to complete your quest.

Sorcerer's Apprentice: This is basically a soft-combo card that you can use when you're ready to exploit a Spellstone or Glyph.   It can help you complete the quest very quickly.   It's also a suitable 2 drop if you need tempo and don't have better options.

Tol'vir Stoneshaper and Tar Creeper:  Vital board protection for the early to mid-game.  Lets you stabilize against aggressive decks and survive until later turns.

Glacial Shard:  This is a great defensive card for the midgame.  I always ship it in my mulligan, but it is surprisingly good for fighting for board against giant monsters (spiteful druid or mountain giants) and also activates the elemental requirement.

Frost Lich Jaina:  Obviously this card is powerful and it can completely swing the game when it's played.  If you have some board against a mid-range deck you can swing the game immediately through the life gain.  Against control decks it is infinite value.  

Mulligans:

Aggro:  Mana Wyrm, Fire Fly, Pyros, Tar Creeper

Control:  Mana Wyrm, Open the Waygate, Pyros, Lesser Ruby Spellstone

Other cards to consider:

Archmage Arugal:  I originally had him in the deck but eventually dropped him because I never had a chance to play him and get value against aggro, and against control I preferred the spell generators to finish the quest.  Worth considering though.   Cutting a Nightmare Amalgam in favor of him is viable.

The Lich King:  Great card and if the meta favors control he's better than Nightmare Amalgam.   Also remember Leyline reduces his cards and his spells contribute to quest completion.

Servant of Kalimos:   Nice value with this card but I feel like he's overshadowed by Bonfire and no longer necessary.

Substitutions:

If you're missing any of the epics or legendaries you can swap in Water Elemental, Servant of Kalimos, or Fire Plume Phoenix.