The ascension of Lucius Banewyrm.

A real grimoire, real magic! You could barely believe it. And not a crappy book on tricks and illusions, the real deal, the most powerful magic to me in history.

And now it was yours, of course you will have to share it with your sister but you are pretty sure a wise choice on your first spells could remedy that if she becomes too much of a hassle.

You both run to the basement of your house. In a corner of it there is a small space closed away by piled cardboard boxes. You built it as kids to become a cabin, a place to hide and play games. Your parents know about it but always kept away from it (you'd like to believe that it is because of a spell you cast in that purpose rather than to give you some privacy.), you know that your sister sometimes use it to masturbate naked. (there is another secret in this secret room, one of the boxes is empty and can be entered from the back. A small hole allows you to spy in the room from it. Only you know about it, you sometimes jerk off in it while watching your sister finger herself.)

You put the grimoire on a board resting on a box acting as a table at the center of the hidden room and light a few candles. (more for ambiance than light or mystical purpose.)

"Ready sis? This is the real thing now, no more child's play and make believe. Today I become a true Warlock. " you tell her as you open the book.

Another element pointing to the authenticity of it, the pages are written in two dozen languages and alphabets yet you understand everything.

The spell range from simple ones like attack spells to more intricate ones that can breach the barrier between worlds or even alter reality itself.

You could be serious and test the book with a rather dull and inoffensive spell but you will have to let your sister Reap the benefit of your test by casting a real spell tomorrow.

You are a Warlock dammit! There is no need for tests or caution. Owning the book, casting spells from it will in time grant you powers of your own.

There are a few things you miss to become a real Warlock, a proper sanctum, a familiar and a few sex slaves.