You will randomly find yourself in battle when in the field, and in dungeons, you will start a battle if you touch an enemy.
Battles are conducted by selecting commands, with a turn-based system.
Some enemies may be surprisingly weak against certain elements. It's always a good idea to turn the battle to your advantage by trying to find these weak points.

You can obtain techniques from treasure chests and from enemies. Just like weapons, you can equip yourself with techniques. There are various techniques: some increase magic power, for example, and some change the range of effects. By equipping yourself with more than one technique, you can combine their effects. However, some magic and techniques don't work well together. You'll need to try different combinations to find the ideal sets.
Also, you can gain a whole range of Boost Manuals from a certain traveling character.
With these Boost Manuals and materials you have collected, you can create new weapons at a blacksmith's shop, or strengthen weapons you already have.
It's a good idea to collect as many Boost Manuals and materials as you can, in order to increase your fighting strength.

In the shrine in Iatt, you can change your class.
In order to do so, though, you need to be at a certain level, and you need to have gained certain items especially for class changes, which will disappear when you use them.
After a class change, the character's title will change, and his/her level will return to 1, but any learned magic and skills will not be forgotten, and the character's previous status will be carried over to an extent.
Characters become stronger with each class change, so it's a good idea to change regularly!