For most persons the experience of astral projection is involuntary and unexpected. They may suddenly find their "selves" separated from their bodies and have no idea how such a thing could have happened; nor will they exercise any control over how long they are out of their bodies, where they want to go or what they want to do in their "soul bodies."
Some persons, however, are either innately cap-able of projecting at will or have mastered the techniques that make it possible. (These techniques are described in The Llewellyn Practical Guide to Astral Projection by Melita Denning and Osborne Phillips.) Among these, a few use their astral bodies as vehicles to attack someone they don’t like.
Interestingly enough, some experts on the subject of vampires believe that this is what vampirism really is. There is no reason to attribute vampire attacks to the physical likes of Count Dracula and his kith and kin, who are products purely of the imagination. There is evidence that real victims of vampires are set upon by a malevolent astral form.