


Hearthstone's first expansion was Goblins vs Gnomes, released in December 2014. Starting with Knights of the Frozen Throne in August 2017, expansions also featured optional solo-player content in the form of Missions, effectively integrating an adventure into each expansion.

In early 2017, the developers announced their plans to release three expansions each year, with each expansion featuring around 130 new cards, abandoning their previous annual release cycle of expansion- adventure-expansion. These expansion cards are obtained chiefly through purchasing and opening card packs, through crafting, or through earning Arena rewards. These cards, referred to as expansion cards, are used primarily to create and build decks to play in Casual or Ranked mode, in either the Standard or Wild game format modes. Expansions introduce the majority of collectible cards into the game, with each expansion introducing around 130-145 new cards. Expansions are major card set additions to the game of Hearthstone.
