If you didn't know the best way to enhance heroes is with time giver, experience giver or life giver. Time giver will give you 2000 exp, experience giver is 4500 exp, and life giver is 10000 exp. If you are farming the hourly dungeon you can get a time giver every time if you do Easy. Normal will sometimes give you two time givers but I've found its better to just do easy mode because you are guaranteed 2x time givers for 20 energy. If you can clear it Hard difficulty will give you 3x experience giver and 1 time giver. This is the best way to get exp as far as energy is concerned and will also save you gold.