Things consider to change:
Topsy Turvy
Forbidden Words
Arena Treasure Chest

into

The cleric/pyromancer/circle healing combo and acolyte (the one who draws a card from receiving damage)

This deck needs better card draw engine. But I leave this one to you.

Introduction:

This deck focuses on counters big decks, I haven't played it much, but it's way better than ordinary stealing priest from classical Thoughtsteal and such. This deck isn't going to be good enough, so I highly suggest you change a deck little bit to deal with aggro like techs and such, because it's not a great deck yet.

Here's the combo you have to play:

Potion of Madness + Wretched Reclaimer

This allows you to stop anyone cheating big minions, mainly Big Priest and others that summon a 1/1 copy of it.
Relying on Wretched Reclaimer alone isn't going to be enough, he can't do everything by himself as if you can only have two copies of it, here is his best friend and the combo:

Lazul's Scheme + Cabal Shadow Priest

If that's not going to be enough, there is also Entomb, with many of these stealing cards, you will win against a decks that has no end-game plan such as fatigue or milling, you basically win, especially if the big minions dies from Spirit of the Dead. However, it's very bad against many other decks, but I'm sure anyone can adjust this deck better than I do.