Recondite Shades of Stygia, the Spectres are beings of Death that can be called upon with a Summoning
Mages call them up for advice on matters of mortality (or, conversely, immortality), loss, grief, the wisdom of the dead, lost civilizations, and The Underworld.
They often resemble beings traditionally associated with death — spectral, robed figures, black dogs, crows, maggots, or obviously dead people.
Sometimes they take the form of deities of death (Hades, Baron Samedi, Mrtyu-Mara, etc.)