Book of Hekate

The Book of Hekate is an artifact of the Goddess of Magic.   It contains spells that most casters have never seen, and typically on require Verbal and Somatic components.  Instead of having specific material components for each spell, they spell only require the caster to possess the Book of Hekate itself.   The book has the following rules that are attributed to it.
Upon Receiving the Book of Hekate:

• You may choose 1 spell from the book that is not counted as known.
• Each level up when you choose your spells, you can replace a class spell with a spell of Hekate.   These selections are counted as known and replace any spell you could have obtained through your class spells.

Rules:

1. The Book is not required to be held in your hand, but must be on person.  It cannot be on another plane or left in a safe place, typically people have it easily accessed.  If the book is taken from you, as long as it is on the same plane of existence it can be summoned back to you.  Bonus action in combat to summon your book back to you.
2. The book cannot be copied from and cannot be used by anyone that has not received it from their god.  Casters that can copy spells from a scroll or books cannot copy these spells to their respective books.  
3. Spells are learned typically upon level with their patron or through forms of tribute through their respective caster gods.  No amount of skill will ever replace needing the book of Hekate to cast her spells.
4. The spells are stored within the persons Book of Hekate.  When they gain access to spells from her book, they prepare them in her book.  If players choose to add a spell from her book as prepared, they forgo the ability to choose a spell from their own book or class.  This applies to known versus unknown, as players do not know every spell in existence.
5. Spell Scrolls with spells of Hekate can be used by anyone, but they can never be recorded to a person's spell book.
6. Classes that have the ability to swap spells at level up, cannot swap their spells for Hekate spells or vice versa.
7. Certain gods may allow players to supplement material components of class spells by using the book.   It is determined by the gods blessing.