Ghul Djinn are very dark Djinn compared to the Marid and Sila Djinn, though this is not something they go out of their way to accomplish. Their connection to death and the many Otherworlds spread throughout the realms of the living lends to their power, though not necessarily in a benevolent way. They are very gifted with all forms of Death magick, up to and including Necromancy. They tend to attract the dead if they linger in one place for too long.
While not intentionally cruel in how their wish-granting functions, their catalysts are often the dead that linger nearby. The energies behind their wish-granting tend to be unpredictable and can create volatile combinations. The group that I work with operates almost exclusively off the energies of the dead near them, so if you aren't familiar with the history of death in your area, they can call upon very malevolent forces to get the job done. Their morals are looser than the average human's, so they often won't think about what may come of a wish they grant. They require an experienced keeper who knows how to work with Djinn and their wish-granting abilities.
Ghul Djinn tend to attract spirits of all kinds over time. They can help you build a repertoire with the spirits in your area for added support in endeavors. They are also quite keen on death magick, and if it's something you work with now or intend to build into your practice, they can enhance your experiences. They are also very good at building your senses and encouraging spirit
communications to help you pick up on your companions easier. They are incredible Necromancers, often able to raise specific spirits to find out information about the area they're buried in or getting their input and advice on odd situations.