Going back to Skrein's question:
"how can you use necromancy on a dead body to cause true death, when their body fades to the death realm when not truly dead"
From Wikipedia: (
http://en.wikipedia.org/wiki/Necromancy )
In addition, Odysseus has to follow a specific recipe, which included using sacrificial animals' blood for ghosts to drink, while he recites prayers to both the ghosts and gods of the underworld.[2] Rituals, such as these, were common practices associated with necromancy, and varied from the mundane to the more grotesque. Rituals in necromancy involved magic circles, wands, talismans, bells, and incantations.[4]
Also, the necromancer would surround himself with morbid aspects of death, which often included wearing the deceased's clothing, consumption of unsalted, unleavened black bread and unfermented grape juice, which symbolized decay and lifelessness.[5] Necromancers even went as far as taking part in the mutilation and consumption of corpses.[5] Rituals, such as these, could carry on for hours, days, even weeks leading up the summoning of spirits. Often these practices took part in graveyards or in other melancholy venues that suited specific guidelines of the necromancer.