It's going right into my wild quest priest. It makes in easier to pull of the quest against aggro, and improves the n'zoth later on. A problem with n'zoth and draw cards is the high probability of it milling you from too many draw/add cards to hand effects, this will help to alleviate that.
If a different version of the quest priest is made that includes the other priest card they revealed, then this will be much better than loot horder because it's much more likely to give you a combo priest and it advances the quest faster. It has the mech tag too, but It's yet to be seen if that is worth anything.