I agree with Neon that Unseen could be a sleeper hit in this event, but this deck is a much more aggressively oriented deck than the one he shared. Play lots of cheap unseen/valkyrie/dinosaurs (12 1-drops, 10 2-drops, 8 3-drops) backed with permafrost and finest hour to remove threats and win trades. Once again, unstable form can be a useful cheap "removal" to eliminate a Sandstorm Titan or a warcried unit. Copperhall bailiff is a 2-of against the inevitable grow-wide brigades/mirror match.
Bisma, the Unseen promo card, is unquestionably the choice here.