The Book of Planes is an Artifact of cosmic proportions. It is an object that Gods and apocalyptic creatures strive to control and own. Entire planes have been known to go to war when a the book is located, because it is that powerful. Gods will sacrifice everything and anything to have the book that controls their plane.  One and only one, physical Book of Planes exists on each and every plane, with the exception of prison planes and most demiplanes where there exists none, for obvious reasons. 

Each Book of Planes looks different, but as a whole they look like an average everyday book that you might find on that Plane. If an individual looks at a Book of Planes and has never traveled to another plane, the book looks like some kind of reference book. The individual quickly loses focus and leaves the book alone. If the individual has traveled to another plane and happens to stumble upon a Book of Planes they have found something incredible powerful. An attempt to attune to the Book of Planes requires only to read its introduction which takes 3 hours. The introduction explains what the book is and how it can be used, thereby imparting the feat "Planar Scholar" upon the attuned individual. The individual then has 9 hours to use the book before it vanishes and reappears in a new location. 

Random Properties. The Book of Planes has the following random properties:

• 2 Minor Beneficial Properties (DMG 219)
• 3 Major Detrimental Properties (DMG 220)

Planar Scholar. After attuning to the Book of Planes, you immediately gain the feat "Planar Scholar." (D&D Beyond, Custom Feat)

Travel to Planes. When flipping through the Book of Planes you will see on each page a heading labeling or naming the plane followed by a window to see the plane that takes up half the page. The window to the plane is ever moving as if from the focal point of a bird soaring through the plane. Below the window you will find, in incredibly small print, the rules that govern that plane. While attuned to the Book of Planes you may travel to other planes, by touching the window to the plane, as if you cast a perfect Plane Shift (Conj. 7th, PBH 266) or Gate (Conj. 9th, PBH 244) spell. By studying the travel section of the book for 3 hours, all future attempts to cast Plane Shift, Gate, or Contact Plane, work perfectly and without reagents.

Create New Planes. While attuned to the Book of Planes you may create a new plane. By removing a blank page from the Book of Planes you can create a new plane, however in order to travel to the newly created plane, you must place the page back in the book thereby adding the new plane to the cosmic multiverse. On the removed blank page from the Book of Planes, you may write the rules of your new plane, these rules should be clear and bullet pointed. Every plane in the Book of Planes has access to the Book of Planes whether in physical or ethereal form - this rule can not be removed, but it may be altered with DM discretion. All newly created planes measure 180 feet by 180 feet; are made of ethereal mist but can support life; and require rules to be implemented withing 24 hours, otherwise the plane implodes upon itself. When a plane implodes upon itself, the blank removed page burns to ash. 

Planar Rules should include at the very least:

• How fast the plane grows and it's size limit. Created planes can not be larger than the creators home plane.
• What Races and Monsters can exist on the plane.
• What materials can be found on the plane.
• What flora can be found on the plane.
• How the flow of magic works on the plane.
• How life and death work on the plane.
• What other planes overlap or touch this plane.
• How to enter or leave the plane. (Other than the Book of Planes)
• All created planes must have an author.

Alternatively, you may also use a removed blank page from the Book of Planes to cast the spell "Demiplane" (Conj. 8th, PBH 231). Once used the blank page burns to ash. Additionally, it should be noted that on created planes, a "Wish" spell may never be cast. Furthermore, if the creator of a plane dies, the plane continues to exist for 1d100 years, after which point the plane becomes the other side of a bag of holding. Once all items are removed from these former planes, they implode. A removed blank page from the Book of Planes  that has not been used to create a new plane or imprison someone/thing, can be used to locate the Book of Planes  with a successful Wisdom (DC 25) check, once per 100 years.

Rewrite Planes. While attuned to the Book of Planes you may rewrite existing planes. When attempting to rewrite a rule you must make an Intelligence check (DC30). If you succeed you may rewrite one rule on one plane, with DM supervision. If you fail, you are imprisoned within the Book of Planes, and you lose attunement to the book, until you die.

Prison. Within the Book of Planes exists a section known as "The Prison." It is at the back of the book, even beyond the blank pages, and it is a place of tortured souls and madness. The Prison houses mad gods, over zealous demons, forgotten angels, apocalyptic creatures, and imprisoned adventurers who dared try to edit a plane. Each page within this section of the book has a planar window into the prison cell of the lonely damned individual. Touching the planar window will transport you to the prison cell and free the imprisoned individual. The only way to free an imprisoned individual is to replace them with another individual of similar size or type. Prison pages may be removed from the book for up to 5 days, at which point the page will disappear and reappear within the Book of Planes. It should be noted there are a few blank prison pages.

Destroying the Book. Attunement to the Book of Planes, as discussed previously, makes the physical Book of Planes vanish for 1d10 weeks before it reappears someplace within its home plane. Every 12 hours after it reappears it travels to a new location within its home plane. Ripping each page from the Book of Planes, makes planar travel from any plane to any other plane impossible for 1d10 days, after which time the Book of Planes reappears whole again. Ripping the Book of Planes in half disconnects half of the planes from the other half of the planes for 1d10 days, after which time the Book of Planes reappears whole again. Removing a Book of Planes from its home plane, will cause the home plane to implode and that Book of Planes to burn to ash. The Book of Planes is immune to all other damage. It is possible to destroy the Book of Planes, but it is not advisable since it will create a cataclysmic chain reaction. Causing any Book of Planes to enter a paradox loop will trigger the destruction of ALL Book of Planes on all planes. When this occurs all individuals imprisoned within the Book of Planes will be released to random planes. Additionally, the Book of Planes will be unable to create new planes, and all blank pages will burn to ash. Following that, one by one, all pages within the Book of Planes will systematically implode and those planes will meet their apocalyptic ends. Once all of creation is destroyed a single blank creation page will float through the darkness until a new cosmos is created. 

Notes: person who has traveled to another Plane.