I suppose the opponent can have a giant or dragon of their own. Only you'll need at least 5 in order to keep just 1 high end card like that because of Mind Control and Shadow word kill. Shadow Word is expensive at least though, isn't it? I mean, Blizzard wouldn't really give a card that kills Ragnaros and only costs 3 mana, would they? At least, not to a class that can take Ragnoaros off me...I mean, that's not OP or anything!
Blizzard, I realise you don't read the posts the community put here, which is why our comments continue to be ignored since the beta. But on the off-chance that you get bored and feel like doing something different, please nerf the 1 class that can so easily create one hit kill minions.