"The Necromancer's Amulet (also known as the Necromancer Amulet) is a legendary artifact created by Mannimarco. In appearance it is an exquisite amulet, often with a skull emblazoned upon it. It grants the wearer magical protection equivalent to plate armor, as well as the ability to regenerate from injury, resist mundane weapons and absorb magicka. The wearer also becomes wise beyond his years and far more capable in the School of Conjuration. This comes at a price, as the amulet can drain the wearer's strength, endurance, health and stamina. The artifact is popular among both thieves and mages. The amulet is unstable in this world, and is forever doomed to fade in and out of existence, reappearing at locations distant from that of its disappearance.
The amulet was uncovered by the Eternal Champion during the Imperial Simulacrum, in either High Rock or the Summerset Isles. In the events leading up to the Warp in the West, the amulet was recovered from an ancient lich by a knightly order in the Iliac Bay area. The amulet later fell into the hands of the Underking, who promised it as a reward for any who would return the Totem of Tiber Septim to him. Due to the Warp in the West, the fate of the amulet is unknown, although it may have been given to an unknown agent of the Blades. By 3E 427, the amulet had come to be owned by Arch-Mage Trebonius Artorius of the Vvardenfell branch of the Mages Guild. It was later claimed by the Nerevarine, although the circumstances as to how Artorius lost it are contradictory, ranging from the death of all the Telvanni councilors to the Nerevarine dueling for the title of Arch-Mage."

~Unofficial Elder Scrolls Pages

Damage Health 50 points
Damage Stamina 50 points
Damage Light Armor 50 points
Damage Heavy Armor 50 points
Damage One-Handed 50 points
Damage Two-Handed 50 points

Fortify Armor Rating 102 Points
Fortify Conjuration 50 Points
Regenerate Health 50% faster
Resist Normal Weapons 50%
Spell Absorption 100%, but damage is not reduced.