The Stone of Darkness is an item in Lost Kingdoms.
Summary
The Stone of Darkness is found in one of the chests in Broch Black. It is needed to open the door to access the boss fight in Broch Black. The stone works similarly to that of a key since it needs to be placed into the door in order for it to open.
Appearance
The Stone of Darkness appears white in colour. It looks slightly similar to that of a goats skull, but it is unknown what type of skull it truly is, or if its one at all. It could possibly be a stone imitation of a skull.