Book of Exalted Deeds

From Dungeon Master's Guide, page 222.

Description
''Wondrous item, artifact (requires attunement by a creature of good alignment). 5 lbs.''

The definitive treatise on all that is good in the multiverse, the fabled Book of Exalted Deeds figures prominently in many religions. Rather than being a scripture devoted to a particular faith, the book's various authors filled the pages with their own vision of true virtue, providing guidance for defeating evil.

The Book of Exalted Deeds rarely lingers in one place. As soon as the book is read, it vanishes to some other corner of the multiverse where its moral guidance can bring light to a darkened world. Although attempts have been made to copy the work, efforts to do so fail to capture its magical nature or translate the benefits it offers to those pure of heart and firm of purpose.

A heavy clasp, wrought to look like angel wings, keeps the book's contents secure. Only a creature of good alignment that is attuned to the book can release the clasp that holds it shut. Once the book is opened, the attuned creature must spend 80 hours reading and studying the book to digest its contents and gain its benefits. Other creatures that peruse the book's open pages can read the text but glean no deeper meaning and reap no benefits. An evil creature that tries to read from the book takes 24d6 radiant damage. This damage ignores resistance and immunity, and can't be reduced or avoided by any means. A creature reduced to 0 hit points by this damage disappears in a blinding flash and is destroyed, leaving its possessions behind.

Benefits granted by the Book of Exalted Deeds last only as long as you strive to do good. If you fail to perform at least one act of kindness or generosity within the span of 10 days, or if you willingly perform an evil act, you lose all the benefits granted by the book.

Random Properties. The Book of Exalted Deeds has the following random properties:
 * 2 minor beneficial properties
 * 2 major beneficial properties

Increased Wisdom. After you spend the requisite amount of time reading and studying the book, your Wisdom score increases by 2, to a maximum of 24. You can't gain this benefit from the book more than once.

Enlightened Magic. Once you've read and studied the book, any spell slot you expend to cast a cleric or paladin spell counts as a spell slot of one level higher.

Halo. Once you've read and studied the book, you gain a protective halo. This halo sheds bright light in a 10-foot radius and dim light for an additional 10 feet. You can dismiss or manifest the halo as a bonus action. While present, the halo gives you advantage on Charisma (Persuasion) checks made to interact with good creatures and Charisma (Intimidation) checks made to interact with evil creatures. In addition, fiends and undead within the halo's bright light make attack rolls against you with disadvantage.

Destroying the Book. It is rumored that the Book of Exalted Deeds can't be destroyed as long as good exists in the multiverse. However, drowning the book in the River Styx removes all writing and imagery from its pages and renders the book powerless for 1d100 years.