Hero Academy 2 has two main forms of in-game currency which can be used for a wide range of purchases.
Gold can be obtained through completing Campaign levels, Challenge matches, or Quests. Gold is available to use in the Store to make Basic card pack purchases. Additional Gold can be bought in the Store in exchange for Gems.
Gems can be obtained through Daily Gem logins, Gem Passes, and Duel chests. Gems are a valuable form of currency in game which can be used to purchase new Campaigns, Challenges, and Premium card packs. Additional Gems can be purchased in the Store with real currency.