A leather book

Matt looks at the leather book, it looks like a collection of different papers, with various corners sticking out here and there, and on the front it reads: Grimore Majika
Looking around and seeing no-one to claim it, he slid over and pulled the heavy book into his lap. Gingerly opening it up to the first page he read the introduction, after a bunch of giving credit to unknown people, it finally got around to saying something interesting:
This book is designed to help anyone become a summoner with time and practice. Contained within this book are the proper rituals and knowledge to summon a large variety of spirits. They are at your disposal, given to us by the 15 gods as tools and are eager to fill their purpose.
The basics of summoning require a matrix, a design, inscribed on something, a particular summoning spell, and a proper offering. These don't have to be perfect, but the better they are, the more potent your summoning will be.
The second part is the binding, speak the final portion of the spell once they've been summoned, and if they consent (and they likely will) they will be bound to you. To stay in this world, they will require to consume some of the caster's body, blood is the traditional way. This consumption fuels the spirit and may be refreshed over time. See section 3 for easy quick summons.

As Matt finishes the passage, the bus arrives. It's the middle of the day, so its only Matt and the driver on the bus and you take a seat in the back. You flip section 3 to see what this book can offer.