Tome of Understanding is a very rare wondrous items in D&D 5e. It does not require attunement.
Wondrous item, very rare
This book contains intuition and insight exercises, and its words are charged with magic. If you spend 48 hours over a period of 6 days or fewer studying the book's contents and practicing its guidelines, your Wisdom score increases by 2, as does your maximum for that score. The manual then loses its magic, but regains it in a century.
Frequently Asked Questions
This book contains intuition and insight exercises, and its words are charged with magic.
The Tome of Understanding is a Very Rare magic item in D&D 5th Edition.
The Tome of Understanding is a Wondrous Items — Wondrous item, very rare.
No, the Tome of Understanding does not require attunement and can be used immediately when held or worn.