You can use this to control gravity in any area of any size that you can see in a 10 mile radius of you. Also all magic damage inflicted on you is cut in half. You don't need spell components, and your spell durations last for as long as you like with this as your spell focus. Your spells ignore resistance. Your spells have double range/radius.

When you cast a spell with an attack roll against someone with a AC of 15 or higher give a +10 to your attack. You get double spell slots.

Do +5 to your AC against magic attacks, and when your opponent attacks you you can instantly counter with a spell.

Your spells do double damage on a spell with an attack roll if you get 5 or more than your target's armor class.

You get a +5 on a DC save against magical effects. 

If you fail on a spell with an attack roll give them the DARK CURSE effect and attack again.

If you succeed on a spell attack attack again and deal damage to them equal to your AC and heal yourself by the damage that your originally inflicted. 

You have a DC save of 23 + Wisdom bonus + Charisma bonus + Intelligence bonus.

Dark Curse - Cut their armor class in half against magic attacks.

Spell Absorption. While holding the book , you have advantage on saving throws against spells. In addition, you can use your reaction when another creature casts a spell that targets only you. If you do, the book absorbs the magic of the spell, canceling its effect.

Notes: Bonus: Magic, Bonus: Spell Attacks, Advantage: Saving Throws, Sorcerer, Warlock, or Wizard, Damage, Control, Detection, Combat, Deception, Warding