 A unique aspect to this game is " room synthesis " : to advance through the game , the player must utilize Map cards that he has found after winning battles to synthesize rooms . The properties of each room ― including quality of items and strength of enemies ― are determined by the Map cards that the player chooses . Each card has a specific effect : red cards affect the number and type of enemies ; green cards affect the power of the player 's deck ; and blue cards affect the properties of the room itself , such as allowing treasure chests or a save point to appear . 
