You can choose to play as one of 4 classes. These classes are
Each classes can combine with a selection of different souls that gives your character specific abilities. The souls are the souls from fallen adventures. You can use the ability of the souls you have merged with. Each class can choose between 8 different souls. You get your first soul at the beginning of the game and you will get two more during the early parts of the game. You usually have all 3 by the time you reach level 10. The souls are rewarded when you finish side quests. You can choose to buy more souls as the game progress. Do not do this early in the game because you need to save your money for other things.
Inexperienced players should choose to build a character that is very specialized. The game really reward specialization and it is easy to end up with a weak character if you try to be a jack of all trades. Save the more advanced builds for when you have become more experienced .
Read more of the different classes and their souls below.