Hero Realms: Dragon Boss Deck - Rules of Play says:
Rain fire down on those who would dare plunder your treasure hoard! The Boss Deck replaces your personal deck in the Hero Realms Deckbuilding Game. With it, play against 1-5 players using Hero Realms Character Pack or against another Boss Deck. The Dragon Boss Deck contains 30 cards: 18 starting deck cards, 9 Treasure Hoard cards, 2 score cards, and the Dragon boss card.