Scale of Onyxia will be the best card of the mini-set. A very good reactive card (which is rare in druid) which can also be used as a proactive one.
Raid Boss Onyxia might see some play in druid but its gonna be unplayable outside druid.
Kazakusan is gonna be a meme.
Curse of Agony will be meme in standard and decent in wild, but I dont think that the deck based around it will be better than current OTK warlock decks.
Furious Howl is gonna be insane in face hunter.