Necromancy is a blend of Dark Magic as practised by the Dark Elves and the Mortuary Cult of ancient Nehekhara. It is the Magic of the dead and the Undead, originated by Nagash. Practitioners, also called Necromancers, can enjoy unnaturally long lives or even cheat death as well as animate and command the dead. In time, however, their body whithers away and they become Liches or, if they fail, Wraiths.
Necromancy is the magic of the dead and the undead. Apart from necromancers, necromancy is also practised by Vampires and liches. It is similar to Amathyst magic in that it concerns with death and afterlife. Necromancers however use magic to cheat death and achieve eternal life, rather than respecting death as a universal given. It is also different in that Necromancers draw from the Dhar rather than Shyish, and are therefore exposed to dhar's evil corruption.
Unlike dark elf Sorceresses and Chaos Spellcasters who are most times protected by their fickle gods, necromancers shield themselves by channelling the energies into dead creatures or Spirits. The necromancer is thus one step removed from the destructive energies but in no way totally protected from them. Only Vampires are strong enough to not be affected, human necromancers are slowly corrupted. The most strong necromancers can overcome this. They defy death and return as Liches. Those who succumb to the dark powers become Wraiths.
Necromantic spells tend to be more subtle and insidious than the Dark Magic used by Chaos. The greatest lure is the possibility of lengthening ones life and even go beyond death. The most outstanding Spell is probably Vanhel's Danse Macabre, which animates the dead, creating whole legions of Zombies and Skeletons, and put them under the command of the Necromancer.
The origin of Neromancy goes back to -1968 IC when Nagash, obsessed with immortality like many in Nehekhara, was learned Dark Magic by a group of Dark Elves who had stranded in Zandri. Nagash mingled his own knowledge of the Mortuary Cult with the magic of the elves and thus created necromancy. He later also succeeded in using Warpstone to enlarge his powers.
Nagash wrote down his experiments in nine volumes, the "Nine Books of Nagash" or "Liber Mortis" which are still, to this day, the prime source of knowledge about necromancy. Copies of the work are spread over the world, sought by Witch Hunters and necromancers-to-be alike.