Seeing as how Discover was well received, somewhere down the road, I could see them expanding it with a meta gaming angle.
"Discover a Quest"
Quests would be conditions you meet in a game after playing the card that gave you the quest.
They could be things like:
"Destroy three minions in one turn",
"Play five cards in a turn",
"Survive for 5 turns",
"Empty your hand",
"Have four taunts on your side",
Etc.
The rewards could depend on the quest or be determined by the quest giving card. You could get a coin, discover a card, destroy a minion, heal, etc.
I feel like this sort of metagaming is inevitable as a lot of established card games tend to add something like it.
It would tend to be a slow strategy, but could be tweaked. I think it could bring another interesting angle to games. They could even do a promo card that gave you dust or gold as its quest reward if played in standard.
Anyone else think this would be fun?