Book of Heroes is a single-player game mode first released on September 15, 2020. It uses a classic linear adventure format with an appearance similar to Dungeon Run screen. Book of Heroes is about telling the journeys and stories of heroes, such as the ones who represent the classes in Hearthstone, like Jaina Proudmoore. Most of the stories told in this game mode are based on canonical stories of World of Warcraft. Book of Heroes features a chapter for each of the ten classes before Patch 25.0.0.158725, as well as Ambassador Faelin, for a total of 100 unique missions or bosses. It is completely free to play and available to everyone. Additionally, completing a story rewards the player with a corresponding class pack, a special card back, or another type of card pack.