I must admit that im kinda confused about this book ...
That all saving throws required Wisdom. O_o
I would presume that Wizards, Necromancers especialy, should be able to unlock its secrets ... but now im not so sure.
//edit:
Also i dont quite understand that Gale cant absorb the book anymore once you read it. O_o
It was "superb powerful artefact of necromancy having even its own semi-inteligence ... that is for single use only" ? o_O