Eldritch Invocation; Bearer of True Names

Prerequesite: Level 9+ Warlock, Pact of the Tome Invocation

Whenever a creature tells you a name it identifies as, you can inscribe it into your Book of Shadows. A creature with it's name written must make a charisma saving throw, with a save DC equal to yours, with a bonus to the save equal to the amount of unwilling names in the book. The creature is not aware when it makes this save, unless it would be willing to fail, but can see you writing. On a failure, it's name is written properly. On a success, it' is written incorrectly. You can cast a spell targeting a creature with their name(s) written properly in your book as if you were touching them, or as if they were within 10ft of you, so long as they are on the same plane of existence. You can cast nonharmful spells on any creature with their name(s) written in the book, regardless of correct or not, as if you were touching them, so long as they are on the same plane of existence. An incorrect name has a 50% chance to backfire upon casting, wasting the action taken to cast, but not the spell slot.

You can cast from this feature a number of times equal to 1 + your Charisma modifier (min. 2). You regain all uses after finishing a long or short rest. Your Book of Shadows can hold a number of names equal to Twice your Warlock level. An incorrect name vanishes from the book 8 hours after it is inscribed.