The Mill Stone is a stone ring with cryptic writings and some strong magic that will stand up against dark magic, and it originated in the depths of the Netherrealm. It made its debut and appearance in the Konquest mode of Mortal Kombat: Deception.
This magical stone protects its owner from any black magic attacks. Some believe it's the ancient markings, similar to the necromancer Quan Chi's tattoos, inscribed on its side that grant its protective powers to whoever possessed it.