…this
has a dual meaning. Some of these lesser demons can indeed be cast out and bound
elsewhere…for others, when you use the keys of imprisonment, you lock the
doors around yourself or around others, so that demons cannot enter to harass
you and hinder your work. In a manner of speaking, you imprison yourself in a
force field, which is impenetrable to the attacks of these evil ones…. …when
you are protected by these keys—they run smack into an invisible wall, or a
very visible fireball, if need be.