When you do not truly have the time to battle the monsters yourself and select the abilities, the auto battle function works very good. It's a great feature that will let you make the battles run very quick, particularly if you use the Auto Battle function together with the 2x Speed. I recommend using this for the very early levels, as the opportunities of you losing the battle are actually near to zero (rather non existing). If you keep your heroes leveled up at all times, the Auto Battle is going to work quite well for the later levels too, so make certain you keep your heroes as much as date at all times.