The Midnight King, the lord of Piston City's underworld, has sponsored a fighting tournament. Heroes and villains from around the world have gathered to compete. Fighters who distinguish themselves in the tournament may challenge the Midnight King himself for a chance to win the ultimate victory.

Each player chooses a unique fighter to control. Players take turns playing their cards. A player may put an arena into play, fight to take over someone else's arena, and train fighting techniques. Fighting techniques are permanent increases to total fighting power, and other cards may temporarily increase fighting power during a fight. Fights are resolved by comparing the fighting powers of the two fighters. A fighter who controls six arenas fights the Midnight King and then either wins the duel to end the game or loses an arena.