The Troll Compass Pendant

The Troll Compass Pendant is an essential part of any ethereal investigators wardrobe.
The arrow or pointer at it’s centre is comprised of two main materials; Copper and Iron.
The Copper has a slight attraction to ethereal energy but is mostly neutral. However, the Iron in the tail of the pointer is repellent to most ethereal entities, especially Trolls, and so will always be pushed away in their presence.
This pointer is then suspended on a rotating arm in such a way that it is allowed to spin freely. This gives the arrow the freedom to point in any direction.
With the Copper of the arrows point being attracted and the Iron being repelled, the compass will always point directly at the nearest ethereal entity.