Jag hittade ett svar på sidan 192 i PHBII under klassfunktionsåterhämtning.
Some class features offer two or more different options, such as the choice of combat style a ranger must take at 2nd level. Class feature retraining allows you to swap out one option for another [...] Upon gaining a new level, a necromancer could change her school specialization to evocation, thus becoming an evoker. At the same time, she could also choose to change her prohibited schools from conjuration and illusion to abjuration and transmutation. Doing so would cause her to lose access to all spells from the newly designated prohibited schools. Even if her spellbook contains those spells, she would lose the ability to prepare and cast them.
Jag är också medveten om att lår inte behöver Necromancy, men debuffing är avgörande för mig. Även Clone. Egentligen är de enda två stavarna jag använder regelbundet Mirror Image och Invisibily, som båda kan väljas till rullar och används med UMD.