The Chthonoi
The Chthonoi is a Greek term signifying “gods of the Underworld”. They were, in Greek mythology, the gods, daimones, and certain elect dead who had power over the land of the dead. The ancient Greek underworld was not a place reserved for the evil, but rather, ALL shades rested here after their life thread had been cut by the Fates. Their souls were guided by Hermes Khthonios (sometimes Thanatos, or his sister Keres), to the river Styx. There the dead gave a coin of payment to Charon, who would then ferry them into the Underworld. Something interesting that one consider is that before entering the graveyard to perform workings, it is paramount that one give a coin as an offering to the gatekeeper lest you not have permission to pass. How similar is that to dead who likewise had to pay?
In any case, those who did not receive proper burial rites or did not have payment, were refused entry into the Underworld. Thus, they were forced to stand on the edge of the river Styx for eternity in limbo, or make their way back to earth to haunt the living. These restless dead were often the most called upon in the ancient Greek defixiones (curse tablets), because they were believed to be the most easily agitated and eager to attack.
There are several important Chthonoi to the Necromancer. The most important being Hades of course.
Hades is the brother of Zeus and king of the Underworld. He is often depicted to be cold and indifferent to offering and sacrifice. Often times, he wad given offerings simply out of respect. However, this is not altogether true. Hades isn’t “warm”, but he’s not cold either. He is willing to speak and teach and happily receives sacrifice. The ancient Greeks were often terrified of him, so much so that they refused to speak his name. Instead, they would refer to him by his epithet Plouton (origin of Pluto). He did have a very small cult, as some archaeological evidence reveals, but not even close to that of the Olympic gods. Hades is a lonesome figure, but not by any means cold and heartless. No Necromantic rite should ever leave him out. He is the God who can raise or put down the dead.
Since he rules everything below the earth, gold, diamonds, and other such valuable items are his to give. And since the roots of plants rest in the ground, he also has the authority to bless one’s garden. Particularly if the plants are of Necromantic nature.
Persephone is, perhaps, more so connected with the fertility of the earth than Hades. This is due to her being the daughter of Demeter, the goddess of agriculture. She is the daughter also of Zeus, who gave permission to Hades to kidnap and marry her. Eventually, she was returned to her mother but on the condition that she return to the underworld during the winter months, due to her eating the seeds of the pomegranate a food of the dead. I find her to be much more cold than Hades. She can quite irritable at times, so it’s best to be very respectful in her presence. Despite this, she has much potential in teaching the Necromancer. She shows concern for the dead and resents ill treatment of them. So much so, she went on to admonish me for planning to evoke the dead to physically appearance as that can be painful for some spirits. But whether you like her personality or not, she is still a necessary goddess to serve. She is the wife of Hades, and he loves her very much.
Hermes Khthonios is an aspect of the god Hermes, who is commonly thought to be a celestial entity. He does, however, have a very powerful job as the guide of the dead to the Underworld. He can, of course, do the opposite and escort the dead from the Underworld with the permission of Hades and Persephone.
Thanatos is the personification of Death in Greek mythology. In particular, he symbolizes a peaceful death while his sister Keres rules violent death. Like Hermes, he was also a figure that guided the souls of the dead to the Underworld.
He is not a God proper, but a daimon. This term is where we get our word “demon”. It translates “divine intelligence”.
Other Chthonoi
There are other gods which I do not mention because I do not interact with them. There are really too many to list so I don’t get into it. But besides Hades and Persephone, Hell is the limit on which gods you can invoke to help you and guide you.
Sorry!