Light for the Necromancer.

I don't know, it doesn't really require any special magic to cast light spells.

It just feels a bit pointless to waste a huge amount of magic points on nothing.

I don't mind spending a lot of magic points on mass blessings. When playing as a Necromancer, I prefer to level up the native schools of magic. Light magic would also be useful if I could level up a dozen skills to expert level. But I'm happy to use it if I can get a light magic tome. Of course, if the slot isn't occupied by a more useful artifact.