The number of cards priests have that either take control of your cards or copies them from your hand/deck is ridiculous.
Priests are using every single one of their cards that do these and it's just beyond moronic.
Take a recent match of mine as an example.
Mind Vision into a True Silver Champion
Shadow Madness on a Loot Horder, swung it into one of my minions, killing them both and drawing him a card
Thought Steal into Gaurdian of Kings and Sword of Justice
Cabal Shadow Priest a Leper Gnome
Thought Steal into a Tirion Fordring and Sunwalker
Mind control Tirion Fordring
I can deal with the stupid Cleric, all the healing, all the buffing and all the instant kills they have but this constant bs of using your cards against you is getting out of hand.
Thought Steal is the worst by far because it increases their deck size by 1 per use without effecting their card draw and it stands a good chance of getting them class specific cards. As a stand alone card it is the most broken card in the game.