In the magical medieval realms of Muster, players recruit forces to their side with the aim of having enough strength to control the most castles by the end of the game.

Castles are home to the realm's five Banners, under which serve soldiers, archers, a knight, a beast, all being led by a king or queen.

Rainbow Wizards join the fray, acting as floating yet powerful wild cards without allegiance, but beware, they are fickle friends who will just as easily switch players as Banners!

At the end of the game, the player that controls each castle is the one who has cards with greater total strength on their side of the game board.