Adder Stone

A glassy river stone with a naturally occurring hole going through the center. By looking through the hole, you can target one creature or space you can see and expend one of the Adder Stone's three charges to look more closely at the targeted creature. When you look at the creature this way, you gain a second sight and see their true nature. If they are a shape changer you see their true form. If you target an area where the barrier between planes is thin you see this distinction and can tell where a portal could be opened, or does exist.