"The word "necromancy" is adapted from Late Latin necromantia, itself borrowed from post-Classical Greek νεκρομαντεία (nekromanteía), a compound of Ancient Greek νεκρός (nekrós), "dead body", and μαντεία (manteía), "divination by means of"; this compound form was first used by Origen of Alexandria in the 3rd century AD. The Classical Greek term was ἡ νέκυια (nekyia), from the episode of the Odyssey in which Odysseus visits the realm of the dead and νεκρομαντεία in Hellenistic Greek, rendered as necromantīa in Latin, and as necromancy in 17th-century English"
So the practice of Necromancy was relevant all through the Greco Roman empire of antiquity ;"
Necromancy was prevalent throughout Western antiquity with records of its practice in ancient Egypt, Babylonia, Greece and Rome" In fact is Homer's Odyssey that we get one of the best overview of the practice.
"Early necromancy was related to – and most likely evolved from – shamanism, which calls upon spirits such as the ghosts of ancestors. Classical necromancers addressed the dead in "a mixture of high-pitch squeaking and low droning", comparable to the trance-state mutterings of shamans. Necromancy was prevalent throughout Western antiquity with records of its practice in ancient Egypt, Babylonia, Greece and Rome. In his Geographica, Strabo refers to νεκρομαντία (nekromantia), or "diviners by the dead", as the foremost practitioners of divination among the people of Persia, and it is believed to have also been widespread among the peoples of Chaldea (particularly the Sabians, or "star-worshipers"), Etruria and Babylonia. The Babylonian necromancers were called manzazuu or sha'etemmu, and the spirits they raised were called etemmu.
The oldest literary account of necromancy is found in Homer’s Odyssey. Under the direction of Circe, a powerful sorceress, Odysseus travels to the underworld (katabasis) in order to gain insight about his impending voyage home by raising the spirits of the dead through the use of spells which Circe has taught him. He wishes to invoke and question the shade of Tiresias in particular; however, he is unable to summon the seer's spirit without the assistance of others. The Odyssey's passages contain many descriptive references to necromantic rituals: rites must be performed around a pit with fire during nocturnal hours, and Odysseus has to follow a specific recipe, which includes the blood of sacrificial animals, to concoct a libation for the ghosts to drink while he recites prayers to both the ghosts and gods of the underworld.
Practices such as these, varying from the mundane to the grotesque, were commonly associated with necromancy. Rituals could be quite elaborate, involving magic circles, wands, talismans, and incantations. The necromancer might also surround himself with morbid aspects of death, which often included wearing the deceased's clothing and consuming foods that symbolized lifelessness and decay such as unleavened black bread and unfermented grape juice. Some necromancers even went so far as to take part in the mutilation and consumption of corpses. These ceremonies could carry on for hours, days, or even weeks, leading up to the eventual summoning of spirits. Frequently they were performed in places of interment or other melancholy venues that suited specific guidelines of the necromancer. Additionally, necromancers preferred to summon the recently departed based on the premise that their revelations were spoken more clearly. This timeframe was usually limited to the twelve months following the death of the physical body; once this period elapsed, necromancers would evoke the deceased’s ghostly spirit instead."
The necromancer is essentially taking the spirit from 'the realm of the newly dead' & its deeply connected with the Greco Roman Underworld. Screw up the necromancy of the Underworld & not even Hades himself can save your PC not that he would. One of Cerberus's litter may come for the PC to drag him or her before the Judges of The Dead.
"Minos, Rhadamanthus, and Aeacus are the judges of the dead. They judged the deeds of the deceased and created the laws that governed the underworld. However, none of the laws provided a true justice to the souls of the dead, and the dead did not receive rewards for following them or punishment for wicked actions.
Aeacus was the guardian of the Keys of the Underworld and the judge of the men of Europe. Rhadamanthys was Lord of Elysium and judge of the men of Asia. Minos was the judge of the final vote."
The Judges of the Dead are key to bridging the gap between the Inferno & the Greco Roman Underworld. These three figures have governance over the fate of the dead even in Dante's Inferno & PC shaman's & necromancers should tread lightly around their affairs.
By the time of early & high middle ages then the practice of Necromancy begins to aqquire its more unsavory reputation among the Catholic Church;
"Many medieval writers believed that actual resurrection required the assistance of God. They saw the practice of necromancy as conjuring demons who took the appearance of spirits. The practice became known explicitly as maleficium, and the Catholic Church condemned it. Though the practitioners of necromancy were linked by many common threads, there is no evidence that these necromancers ever organized as a group.
Medieval necromancy is believed[by whom?] to be a synthesis of astral magic derived from Arabic influences and exorcism derived from Christian and Jewish teachings. Arabic influences are evident in rituals that involve moon phases, sun placement, day and time. Fumigation and the act of burying images are also found in both astral magic and necromancy. Christian and Jewish influences appear in the symbols and in the conjuration formulas used in summoning rituals.
Practitioners were often members of the Christian clergy, though some nonclerical practitioners are recorded. In some instances, mere apprentices or those ordained to lower orders dabbled in the practice. They were connected by a belief in the manipulation of spiritual beings – especially demons – and magical practices. These practitioners were almost always literate and well educated. Most possessed basic knowledge of exorcism and had access to texts of astrology and of demonology. Clerical training was informal and university-based education rare. Most were trained under apprenticeships and were expected to have a basic knowledge of Latin, ritual and doctrine. This education was not always linked to spiritual guidance and seminaries were almost non-existent. This situation allowed some aspiring clerics to combine Christian rites with occult practices despite its condemnation in Christian doctrine.
Medieval practitioners believed they could accomplish three things with necromancy: will manipulation, illusions, and knowledge:
Herbert Stanley Redgrove claims necromancy as one of three chief branches of medieval ceremonial magic, alongside black magic and white magic. This does not correspond to contemporary classifications, which often conflate "nigromancy" ("black-knowledge") with "necromancy" ("death-knowledge")."
Still one could find among the clergy those priests & bishops who not only know the practice of Necromancy but how to effectively put it to use among the world the best possible use of the demonic spirits conjured. This is where to best use Lamentations of the Flame Princess or Dark Albion & it Cults of Chaos for the demonic spirits profiles especially the fire & 1st level Summon spell from Lamentations. But then things change around for Necromancy by the time of John Dee & Edward Kelly. Your hireling necromancer might have in fact looked like this.
"In the wake of inconsistencies of judgment, necromancers and other practitioners of the magic arts were able to utilize spells featuring holy names with impunity, as any biblical references in such rituals could be construed as prayers rather than spells. As a consequence, the necromancy that appears in the Munich Manual is an evolution of these theoretical understandings. It has been suggested that the authors of the Manual knowingly designed the book to be in discord with ecclesiastical law. The main recipe employed throughout the Manual used the same religious language and names of power alongside demonic names. An understanding of the names of God derived from apocryphal texts and the Hebrew Torahrequired that the author of such rites have at least a casual familiarity with these sources.
So what does all of this actually mean for the PC's? It means that there is far more to the necromancer then the traditional fantasy table top pop culture reference. The necromancer can be both an outsider occultist, a respected expert of the clergy, or even a pagan shaman helping to easy the passage of ghosts to the Underworld. Yes there are the rare raging outsider necromancers who want to raise the hordes of the damned for their demonic masters but there also those who help to resurrect the dead.
Those who wish to venture into the 'realm of the newly dead' which is an off shoot of Purgatory & Limbo. This is done via a new necromancy spell called Doorway to the Devil's Hour.
Doorway to the Devil's Hour
4th level Grey & 3rd Level Black magic spell
Casting time: one hour
Duration:5 hours Area of Effect: Self & 1d8 others
This spell must be cast between the hours of three & four A.M. on New Moon. The caster must have a grounding in the arts of necromancy & have over 2oo gold pieces worth of ceremonial garb & set pieces ready for the act including a brass door fashioned with the names of the chief angels of Purgatory & Death on its top. The names of the Judges of the Dead on the bottom of the door overlaid in tin & silver. The door must be erected inside a crypt or ancient barrow.
There will be a knock on the door after the ritual of the spell is cast. A spiritual guide will appear after the spell is cast & escort the party into the realm of the newly dead to escort the spirit back to the material world. There is no guarantee that the guardian spirits & demons will want to see the resurrected spirit back on Earth before they are assigned to their final reward. The PC's may have to fight their way back to Earth & there could be unforeseen side effects of having visited the realms of the newly dead.
This of course ties in with many of the Pulp elements of the classic era. The guardians & judges of the dead are going to impact hard on those who have interactions with the realms of the dead. Undead are some some of the hazards of those who interact with Hell or the various para realms of the dead.
The art of necromancy crosses into the line of the realm of the spiritual. Newly dead PC's are still in the corridors of the half angels & demons which are aware of & can interact with these spirits. But Heaven help such a PC who attempts to aid such a spirit. The Amazing Adventures Book of Powers for the Amazing Adventures! Rpg has all kinds of options for creating PC's who can help a modern necromancer or occultist. The Arcanist might have many of the abilities of a Castles & Crusades necromancer but they are vulnerable to certain aspects of the Amazing Adventures game rules.
Necromancers could actually be the focus for a cell of demon or monster slayers who see the black arts of the necromancer as nothing more then the work of dark forces. Their divine mission may be to slay any & all such fools as those who dabble in the realms of the dead.