Head to Succubus Tower and go upstairs to libary. Go to section 'Read Books' then head downstairs to Rinny. She asked the danger of magic possibly backfiring, then you answer 'Alerting the Watchers', then Boom!!!... magic on the way.
Hmmm, as far as Im aware....and to get that Its a long time since I do this....
But in order to find the "Alerting The Watchers" option, you need to go to the library to ask some of the NPCs there. However, there's a catch. You are in succubus territory, and as such, they wouldn't tell you if you aren't feeling lustful, though.
What you may need to do here is to try and get your...uhm, lets say, arousal high enough to talk to the succubus. You can prolly just grind that by reading the books in the Succubus Tower's Library.
Ye. You dont have to worry about level requirement, you just need to grind up arousal enough to interact with one of the succubus npcs inside the library.