Dominic's Field Guide to Language (Patreon)

Dominic's Field Guide to Language
Wondrous item, uncommon

This magical book is filled with strange, shifting writing. While holding the book, you can use an action to speak its command word followed by a language of your choice, causing the book's pages to become filled with translations between Common and the language you chose. This property can't be used again for 24 hours. When found, the book's pages are filled with translations for a random language.

You can read the book over the course of 1 hour, which can be done during a short rest. When you finish reading, you can magically speak, read, and write the chosen language for 24 hours. Only one creature can read from the book at a time.

'For when the need arises, but you don't want to practice.'
—Excerpt from the foreword of Dominic's Field Guide to Language