Can I play in a Tournament if I don't belong to the Ladder?
You must be a member of the Ladder to play in that Ladder's Tournament.
When you register for a Tournament, you will automatically join the Game Ladder
hosting the event. The system will notify you if you are already a member of
another Game Ladder, and give you the option to cancel your registration.
You can only belong to one Game Ladder per type of game.