These types of spell are not black magic spells but are casted for getting things by force and also for revenge purpose etc. here are few examples. If someone has troubled you a lot and you are very much mentally disturbed and have ruined your life. If your love has left you for someone else, or if you trusted someone has betrayed you, for all these purpose revenge spells are casted. So that the person who has troubled you so much will be punished by revenge magic spells and will realize what he or she has done.
Also revenge spells can be casted for many other reasons, it can be family, love, personal, office, court anything as spiritual spells are very strong and can do wonders.