In Hero Wars: Dominion Era, you can either battle manually or on auto:
In auto mode, the first skills are used automatically as soon as heroes gain enough energy.
In manual mode, you activate your heroes’ first skills whenever you want, provided that there is enough energy.
Auto Mode Availability
Auto mode becomes available at team level 10. It is always active in Arena and Grand Arena and cannot be turned off.
Auto mode is always on in Arena and Grand Arena
Manual Mode Availability
Manual mode is available in Tower, Campaign, Guild War, and other game modes. To fight manually, click the Auto button in the bottom-right corner of the screen. When auto is off, the green circle becomes darker.