The Spell Book

In this world the only magic that exists it's the Spell Book. It choses someone on their 18th birthday to be it's owner. It's method is completely random so anyone has an equal chance. Once it has an owner it will give them one spell. Using spells will please the book and once it's sufficiently pleased will give another spell to it's owner. The Spell Book can only be read by it's owner. The person chosen will be the Spell Book owner until the end of their natural life or until they break one of the Spell Book rules.

The book transcends reality and as such are not bound by it. Even if it's physical is destroyed, it's owner can summon another with a single though. By the same logic even if the Spell Book isn't close of it's owner it can still be summoned with a single though.

The only bounds of its power are it's own created set of rules:

1. You can't use any spells to purposely harm anyone under 18 years old, as the Spell Book still see them as possible candidates.
2. You can't use your spells in a way that can harm the survival of the species you are part of, as it would show a lack responsibility.
3. You can't use your spells to live forever, as the Spell Book don't like the idea of having the same owner for the eternity.
4. You can't tell anyone who isn't bound by your spells about the Spell Book, as the knowledge of it's existence could lead to countless conflicts.
5. After you read this rule you have to cast a spell at least one time per week, as a power without use is pointless.