[Radek]

The warlock. The description of this role in the manual is misleading, errorneous, and confusing. Therefore:

1. All magic schools are native to warlocks. Among others, a warlock can learn all level 7 spells at skill level 7 in the corresponding ...craft skills (and, of course, at character level 7).

2. When you become a warlock, you will gain only Moon and Fiend magic schools. Even if all magic schools are "yours", nobody will teach you the remaining magic schools and you will be able to use books of magic and get new spells during leveling up only in those magic schools, which you already know, i.e., Moon, Fiend, and the magic schools from your role history.
Keep this in mind if you want to develop a universal caster able to learn any spell. Such universal caster must be a warlock or a zenmaster. If you select a warlock, then you will need to get Spirit, Vine, Fire, and Stone magic first and then become a warlock. The warlock will get the remaining magic schools (Moon and Fiend) and become a universal caster. If you select a zenmaster, then you can forget all problems. A Zenmaster gets all magic schools on his promotion.
Note: Naturally, any character of any role can become an universal caster - but the character must learn all level 7 spells during his role history when the corresponding magic schools are "his".