Hero Experience (commonly known as Hero's EXP) is one of the primary resources used to level up your heroes in AFK Arena.
A valuable way to earn Hero Experience is the AFK rewards chest, the amount of Experience you can obtain from it depends on your Campaign progress. You can also get some Experience from Campaign quests and from King's Tower Rewards. Additional Experience sources are also consumable Items (6- and 24-hour Experience chests).
Because the resource is relatively hard to obtain, it is a major obstacle in a player's game progress at some point during the game.