To set up the game, you choose two heroes (all come with a different ability but the same amount of health points) and a dragon to fight against. Your goal is to kill the dragon before it slays your party down to its last member. Although the total health of the dragon scales with the number of players, you may want to increase the size of your party to lower down the difficulty. You then draw two cards for each hero in play.
In each round, you first draw a card for each hero, and then either pick one to play, or draw an additional one. You also draw a card for the dragon from the corresponding deck. Cards come with a priority number and they are resolved from lowest to highest. The dragon card may summon a minion or attack your character. Your hero cards may attack minions, attack the dragon, etc. Some hero cards may offer you a choice, and others may have a random outcome, depending on the flip of a coin.
If you did not defeat the dragon in 14 rounds, you lose. If you are victorious, you may try to fight another, more dangerous dragon.