Mordecai and Rigby find themselves looking for a new form of entertainment when Benson bans them from video games. Deciding to try something new, they find themselves at a store purchasing a new card game that they've heard of. It's easy enough, Mordecai and Rigby find they are actually good at it and start bringing more people into the game not realizing that the more people that join...the strong it gets. Soon the whole park is taken over by fictional creatures and it's up to Mordecai and Rigby to save the day--if they can stop trying to outdo each other first.