The Deadman's Noose

One of the Artifacts of Skaldor, the Deadman's Noose is one of the most remembered and most highly sought weapons on the Illirian continent.
The Noose is a large coin wrought of rusting iron, jagged and sharp at the edges and depicting a skull for the obverse side and a fraying noose the reverse. Despite it's tarnished appearance, it still reflects light extremely well. It was crafted in the blackfire forges of The Dreaded Onefor Skaldor the Conqueror. When the coin is masterless, the first person to see it becomes slowly obsessed with it, gradually losing their mind in pursuit of the artifact. Once they have it, the madness takes hold fully and they begin to perceive everyone as a threat to the coin. They become compelled to kill to protect it, and once they have done so for the first time the bearer of the coin unlocks dark power, becoming a creature known only as The Hanged Man. 
The Hanged Man is stronger than average, and fully ignores pain. They do not eat or sleep, and each kill makes them faster and better skilled with their weapon of choice. In this state, the coin compels the Hanged Man to murder everyone they can see or hear until no one else is around or they are defeated in combat. Once out of victims or killed, the Hanged Man drops the coin, which waits and waits until a new host discovers it. Each Hanged Man inherits the memories of the previous ones and a small amount of their abilities. 
During the Sylvan War, the coin was sent to villages of Elves weeks before Skaldor's horde was due to arrive along the warpath. When the soldiers reached the target settlement, they would find dead farmers and a village's worth of supplies. This was possible because the coin cannot affect the undead or constructs, either of which would be sent to recover it and send it off to the next village.