Blackjack Stunner - The effect seems strong enough to justify running 2-4 secrets (the new ambush secret comes to mind). A targeted freezing trap on a stick seems really good.
Sightless Watcher - Just another pretty solid card. Good statline for 2 mana and lets you fish for mana curve, lethal, outcast, ... more reliable.
Kael'thas Sunstrider - Although already in game I think the effect might be abused in the upcoming expansion. Maybe with the new druid spells or a only spell+kael mage deck. I cann see nerfing this card to "once a turn"