Battle City Rules were used, with the addition of a Deck Master. The Deck Master is an extra card that applies Continuous Effects to the field of the player who controls it. It can be Special Summoned to the field in its regular monster form, but if it is destroyed while on the field, the player automatically loses. Deck Masters can be changed during a Duel if they are Tributed for an effect, or if they are used as a Fusion Material Monster the Fusion Monster is then treated as the Deck Master. Once on the field, the Deck Master cannot be returned to the Deck Master Zone, except by its own effect.