Black magic is the use of unseen forces upon another person against their will. Defending against these dark arts effectively requires an awareness of evil spells and entities, and the strength of will to avert, or avoid, any magical attacks that come your way.
Any misfortune can be thought to have some sort of dark art at its source. Real black magic manifests itself as bad luck rather than fire and brimstone. Knowing what evil entity, if any, hurled a black spell in your path is not critical. That being said, there are only two or three major sources of evil magic.
Black magic pretty much looks the same, regardless of the source. Whether or not bad luck is caused by dark arts and evil spells, it can be successfully defended against.
"Magic, like water, always seeks the easiest course to the sea," says Donald Tyson in his article What is Magic (Llewellyn Encyclopedia). "Once a desire has been formulated, and a ritual conducted to bring it about, magic acts in the simplest and most mundane way to allow the fulfillment of that desire." This is why symptoms of black magic attacks and bad luck are similar.
Recognize these traits as they develop within yourself. An attack of the dark arts will always give signs like these, inside the victim, no matter what the evil spell is intended to do.
Visualization and focus are needed to prevent an evil spell from succeeding. Several steps may be taken to prevent evil entities from attacking magically:
Negative thoughts serve as self-fulfilling prophecies, and this spell will cast that thought out before it can take hold as misfortune. Black magic is simply the focusing of the bad things that happen every day, and are focused by our own negative thoughts. Whether it is dark magic or a dark mood, this spell will defend against the negative energy.