Evocation is a term which has a much more specific meaning than invocation. It is the type of magick which many people feel least at ease with. With evocation, the purpose is to cause an entity to become present within a particular space which is outside the body of the practitioner, and usually to take on a "visible appearance". This may be as a vision astrally or within a crystal ball or black scrying mirror (a black shiny surface upon which are seen images), as a figure seen within the patterns of fire or smoke, or simply as a "materialized" form within the space.
Evocation is a technique that is used somewhat infrequently. It is used in dealing with entities with which the magickian does not wish to share consciousness with. These are usually "demons" although it is, in theory, possible to evoke anything. Despite the obvious impressive nature of evocation, invocation has been said to be a more reliable technique that is less fraught with errors. The idea that some things are so evil they must not be allowed in contact with the magickian has also been questioned. It has been suggested that this idea points to certain shortcomings and fears within the person who holds it and that the way to achieve true balance is to integrate everything and to acknowledge, address and sublimate those "demons" that are found within every human.