Book of Countless Pages

This magic book was the result of a dying scholar's waning willpower, who wished for the spread of knowledge and was sentenced to death for it. The blank pages appear as mundane paper bound in a leather binding with no apparent book or author name. By speaking aloud the name of a nonmagical book you have read before, the Book of Countless pages becomes an exact replica of the book you named and stays like that until it is read fully by a creature or the holder names another one. You cannot name another book until you finish a long rest.

The term magical books mean magic items like tome of understanding or manual of stone golems, not books, guides or notes about magic. At the discretion of the GM, it could be used on spellbooks of wizards.