Gem of Interment

This crystal was supposedly made by the Reaper himself, in order to create his own family. Anyone who holds this sinisterly glowing crystal is tormented by the Reaper's voice and their soul will eventually be dominated by him. During the great war, the demon who stole this crystal from a lesser Reaper was driven insane and began slaughtering people indiscriminately. Eventually, the demon was hunted down by his own kind for his deeds, and was buried together with the crystal. This particular crystal has never existed in the world since then.