Mastermind cards (総大将, Soutaishou, Supreme Commander), rendered on the cards themselves as MASTERMIND are a Character card Class in Genso Suikoden Card Stories.
Overview
Mastermind cards are unique compared to other Character cards in that they are missing many of the attributes of Character cards (Links, Attack, Soldiers, Construction), are not played in your main deck, do not count towards your deck size of 50 cards and have a limit of one per player.
A Mastermind card does invoke the Unique Rule, meaning that any character that shares the Mastermind card's name cannot be played in either your or your opponent's deck.
Mastermind cards tend to carry powerful effects that aid the player or hinder their opponent in large ways. Their far reaching abilities make it so that the choice of Mastermind card can radically effect how one would wish to construct their deck to take advantage of this.
However, Mastermind cards can be very limiting as they can only be used if every Character card in your deck with a camp allegiance, shares one with your Mastermind card. Some Mastermind cards can accomplish this easier than others.