Spells are cast secretly from your hand to alter a monster arena fight without the referee catching you. You bet on specific fantasy creatures before the round starts, then use spell cards to buff your pick or weaken an opponent's monster. The trick is that each spell has a mana cost, and if the total mana on a monster exceeds the referee's limit, that monster gets disqualified at the end. It is a quick card game about managing your hand and reading when to dump your bad cards. The cards are small, but it fits in a pocket.