Yes, it does count everyone's cards. So if Maralynn of the Mornsong is in play, this card is totally worthless. So what do they do if you give them a card they can't use in time? They discard it. And guess who's happy when they do that? This guy:This creature is my zombie wizard tribal leader. I use him with Lich Lord of Unx to make hoards of zombies and wizards. And they're all bigger. And then, Blast of thought will also give you a zombie. Genius!
Tomorrow, a new keyword (psudeo) and the color Wizards usually don't appear in!