Hearthstone's next expansion will focus on the Lich King Northrend and the Knights of the Frozen Throne. The expansion arrives in August with 135 new cards and free single-player campaign content, complete with legendary rewards. The campaign spans a prologue, 2 wings, 3 bosses, and an epic showdown against the Lich King. Each class can pick up a legendary Hero Card in this set. Cards like this turn your hero into a Death Knight by "taking over" their portrait and giving them access to new abilities, much like Jaraxxus does in the current game.