Make the black tome more usable
Similarly to boots of great speed, the black tome is another artifact needing improvement so it is somewhat useful. I suggest:
* halve the corruption caused by reading
* make it always learn a new spell
* make the reading success only straigt literacy check without taking class, level, concentration, learning etc into account so that mindcrafters and barbarians have a way to learn spells. The spell knowledge on successfull reading should be calculated normally