Im worried about quest mage. Either that deck is bad or it is insanely busted. That's my pick for card most likely to see a nerf. What an unfun and uninteractive way to lose.
Yeah, the mage quest seems to be very suspect in terms of balance. At first I thought "Well I'm sure Blizzard made sure to balance one of the featured cards in their new set" but then I remember that Hearthstone has never been properly balanced.
it's about as slow as freeze mage and will probably be as hard to pull off so I doubt it'll be dominant. The decks that ruin the game are easy, slam down things on curve like jade shaman
I think Quest Mage would be great for the game if it was good. A deck doing something different than everyone else which requires lots of thinking about how to play out your turns.
That said, I would be very surprised if it was good. Completing the quest eats up so much mana, and so many card slots in your deck