Tomb of Divine understanding

This divine book is of great value to divine spellcasters of good alignment (LG, NG, CG). Study of the work requires one week. Upon completion, a Good caster gains a +1 divine bonus to the ability score controlling his or her divine spellcasting ability and experience points sufficient to place him or her halfway into the next level of experience. (If the reader has levels in more than one divine spellcasting class, he or she must choose one of the classes to be affected.)
 Evil or arcane spellcasters (LE, NE, CE) are permanently drained of 1d4+1 points of Constitution and must atone (see the atonement spell) in order to gain any further experience. Anyone incapable of casting divine spells who reads even a single word of the work must make a Will save (DC 20) or suffer insanity (see the insanity spell). Except as indicated above, the writing in a libram of divine magic can’t be distinguished from any other book, libram, tome, or so on until perused. Once read, the book vanishes, never to be seen again, nor can the same character ever benefit from reading a similar tome a second time.
Caster Level: 19th; Weight: 3 lb.