Personally I think this is the far more effective anti-zoo card: Unstable Ghoul
Can easily put him in most decks as a replacement for whatever 2 drop you have in there right now to stall aggro. Needs a Flame Imp to kill him (unless they waste one of their Soul Fires), and he takes the Flame Imp with him + hits all those pesky Priestesses and Blood Imps and Abusive Sergeant's too, taking them out.
I think it will be enough to cripple Zoo decks enough to get more decks into mid/late game where they begin to shine.