Tundinzarn

Tundinzarn is an extraordinarily powerful artifact. It's also called The Book of Other Doors. Physically, it is a massive tome, approximately 20x14x6 inches. It's cover is a black scaly leather and it's fitted with silver hardware, including a lock.

The pages are allegedly made from an assortment of materials, from vellum to parchment to human skin.

According to legend, each page has a different affinity to a particular spot in the multiverse. A page can be used to transport the user and anyone touching them to that spot. The legends disagree on how fast the travel takes: instantly, hours, months, or even longer.

Over time, some pages have been torn from Tundinzarn, likely to prevent a user from traveling to that spot. Once separated from the book, a page takes on new, different properties, becoming a distinct magic item. For example, a page for the elemental plane of Fire might function as a Wand of Fireballs, while a page for the Abyss might summon a demon.

Some legends indicate that Tundinzarn is sentient. These legends suggest that the book is motivated to recover its missing pages.