Text (ET): Each opponent who controls more creatures than you can't play creature cards. The same is true for artifacts, enchantments, and lands.
To be more complete: An opponent who controls more creatures than you can't play creature cards. An opponent who controls more artifacts than you can't play artifact cards. An opponent who controls more enchantments than you can't play enchantment cards. An opponent who controls more lands than you can't play lands. [Eventide FAQ 2008/07/08]
This does not stop effects from putting cards or tokens into play. It just prevents them from being played onto the stack (or in the case of land, simply being played). [D'Angelo 2009/02/07]
