Card would have been one of the bosses encountered on King Dice's game board. In the finished game, Cuphead and Mugman can roll a die and progress a number of spaces. Depending on the space they land on, King Dice will transport them to a different battle with one of the casino bosses.
In Card's boss fight, the boss would remain motionless on the right side of the screen. However, card suit projectiles would descend from the top of the screen, landing and weighing down a spiked platform that the player would be under. The projectiles would follow the player's movement, and if they matched three suits of the same kind, they would vanish and lighten the platform. The intent was to defeat the boss while also managing the platform, which could be played like a hybrid of the games Tetris and Bejeweled.
Card was likely scrapped early in development, as its placeholder graphic is crudely drawn, and it cannot take damage or be defeated. It was likely cut for its gameplay being too difficult both to understand and perform, as well as to likely shorten or make the level easier.