At the very early levels you will have the possibility to level up the heroes totally free. This is great to benefit from, considering that it will help you battle the monsters with the Auto Battle option. The building upgrades are also readily available free of charge early, and a few of them will be needed to complete the mission line. If you are a little impatient you can pick to do these upgrades free of charge, however a few of them will need you to wait, so it's finest if you will invest that time doing what we will recommend in the next area: battle monsters.