Blizzard Entertainment was really busy at PAX East. Not only did the company announce two new characters for its upcoming team shooter "Overwatch" and a new character and map for "Heroes of the Storm," but it announced its next big expansion for the popular card-collecting game "Hearthstone: Heroes of Warcraft."

The expansion is called "Blackrock Mountaiin," and it follows the Hearthstone Adventure release model that the game's first expansion "Curse of Naxxramas" established in 2014. The expansion explores Blackrock Mountain, which was a raid from the early stages of "World of Warcraft," before any expansions were released. Blackrock is home to a long-lasting conflict between the resident Dark Iron Dwarves, dragons and elemental creatures. Players will fight many of the iconic bosses and characters that gave the original Blackrock Mountain raid character.

"There are Dark Iron dwarves living in this mountain," Blizzard's Eric Dodds told PAX attendees. "They summon a fire lord to work for them, and he showed up and enslaved them and brought a bunch of fire buddies to hang out and tell them what to do....His goal is to take over the world. There is also a great dragon and Nafarian who also want to take over the world. You get in the middle of this power struggle." 

The expansion will have 17 bosses that will be spread out across five different wings. Starting in April, Blizzard will open one wing a week and let players fight off a variety of bosses in order to get access to a new set of cards. At the end of the Hearthstone Adventure, "Hearthstone" players will have 31 new cards to play with. Players can preorder all five wings of Blackrock Mountain for $24.99, or they can spend 700 in-game gold on each wing.

"Blackrock Mountain" will be available on Mac, PC, iPad and Android on release day.