SOLVED. Fantasy novel where a creepy character has a mind control power called Beguilement. [s]

[Antony]

I have hazy memories of reading a Fantasy book in my teens. The only concrete thing I can remember about the book is that at least one character (I think a creepy and manipulative character) had a power called Beguilement (like mind control). I think he was a professor or tutor to the main character, who was probably a teen boy. I think it might have been implied he was using this power for sexual reasons.
I read it probably 20 years ago and I don't think it was new then.

[Gillian]

You might have luck with one of these lists https://www.goodreads.com/list/tag/mi....

[Bryn]

This is almost certainly King's Blood Four -- it ticks all the boxes (student/teacher, Beguilement, fantasy).

[Antony]

Bryn (Plus Others) wrote: "This is almost certainly King's Blood Four -- it ticks all the boxes (student/teacher, Beguilement, fantasy)."

This seems to fit perfectly as I also remember there were very strict rules to magic classifications and I had vague feelings of chess or strategy games.

I think we can move this one to solved - thank you so much!