The Merlin Big Box contains a new expansion, Morgana, as well as the Arthur and Knights of the Round Table Expansions, as well as the two Queenies. It also features some upgraded components.
Morgana adds three new expansion modules which may be played in any combination with the base game of Merlin or the other expansions:
Morgana: Players draft a purple dice from a common pool to gain special abilities.
Market: On turns that you are not able to complete a mission card, players are allowed to take one time bonuses from the market board.
Caerleon: New locations replace the principalities of the base game. In each location, which are randomly placed, players gain a specific resource or take a specific action, receiving a bonus if they use a specific henchmen.