Book of Ineffable Foulness

Wondrous item, very rare

This work of dark vileness is extremely beneficial to evil clerics. A week of intense study is required to fully digest its wicked contents. After this accomplishment, the evil cleric will gain 1 point of Wisdom and the experience points necessary to place the character exactly halfway into the next level. Once the book has been used this way, it cannot be used again in this manner for a year and a day.

A good character who handles the book takes 5d6 necrotic damage.

A neutral character who handles the book takes 5d4 necrotic damage. A good character who reads any of the pages inside will have a night hag come attack them the next time they attempt to take a long rest (and every long rest thereafter until they or the hag is destroyed). A neutral character reading a page must make a DC 16 Wisdom save or turn evil. A good cleric perusing the pages of the Book of Ineffable Foulness must succeed on a DC 16 Wisdom saving throw or die. If they survive, they must make an additional DC 16 Constitution saving throw or become insane with only a wish able to reverse this effect. In the latter event, even with a successful saving throw, a good cleric loses experience points to place the character at the beginning of the previous lower level.