De Offectibus - Ritual

Lost in a forest, lighted by the moon, you hear a strange shout, and you discover a campfire between 4 monoliths. A book opened is laying on the floor. Nobody here. But when you try to approach, the book looks like mooved by magic and comes directly in your hand. You can't drop it, or even leave the place. The only thing to do is to try the perform a weird ritual, hoping to be free when it will be…