When you are Level 20, go to Grand Master Xenos (Gludin) to become a Dark Wizard. By l2hub
Steps from the game client
Four Seeds
Quest that must be fulfilled to change occupation to Dark Wizard. Witch Varika speaks of the four seeds representing anger, despair, horror, and lunacy. One who obtains them all may become a Dark Wizard. She gives you a seed of despair and asks you to find the rest.