Necromancer's stone

A necromancer's stone was a fist-sized black sapphire used in necromantic summonings.

Powers
Unless it was being used, it had to be covered at all times with a probably magical cloth. Anyone sensitive to the arcane could feel its magical emanations when in its close proximity.

When uncovered, the gem would start pulsating, sending a summoning call to any undead in the area. It also helped controlling more powerful undead, like mummies; when that was the case, the stone started glowing with an eerie black-purple luminescence.

History
When the imp Druzil sneaked into Barjin's chambers, he started checking all of his belongings, among them, the necromancer's stone. Said stone would then be used during the plan to destroy the Edificant Library, where Barjin would uncover it in the catacombs, which summoned a group of ghouls and also helped control a powerful mummy.

The stone would finally be stolen by Druzil, who stepped into the flames of Barjin's brazier and into the Abyss, abandoning the library until Barjin had things under control.

Notable Owners
Barjin, a cleric of Talona who dabbled in wizardry, necromancy and sorcery possessed one of these stones. However, Druzil, Aballister's familiar took it with him when he left the Edificant Library.

Appearances

 * Canticle