Knights of the Frozen Throne adds 135 new cards, including the new Death Knights. These replace your Hero character with more powerful variations. The set also focuses on Deathrattle effects and Lifesteal, a new keyword that heals your Hero for damage dealt. The expansion also has a single-player campaign. The prologue and first wing, The Lower Citadel, are open now, and additional bosses will become available during the next two weeks. Beating the prologue nets you a free Death Knight Hero card, so it’ll be worth playing.
Hearthstone is able to stay relevant because of constant updates, and expansion are the biggest and most exciting for fans. The introduction of so many new cards shakes the game up, giving players a chance to try out new decks and strategies.
Of course, it also encourages people to spend money on new card packs, which is what keeps Hearthstone so profitable.
This is the second of three expansions Blizzard has planned for 2017. The first, Journey to Un’Goro, came out in April. We can expect the third to come out in about four months.