Middle Earth: Sunset of the Fourth Age
Bridge stones are small, sapphire-like enchanted stones. They can form bridges between each other, and detect each other.
They can detect all other stones within a half a mile.
They can connect to another stone within 500 yards and create a 35-foot shimmering, translucent bridge to it. The bridge is incomplete; it consists of a moving platform. The platform moves automatically from the initiating stone to its partner. The destination stone can then be used to dissipate the bridge.
The bridge is large enough to hold about a dozen mounted people, or about 50 unmounted.
The remaining elements of the stones’ operations are unclear. At times the platform has behaved differently. And it is completely unknown how abnormal events – sudden disconnections, multiple bridges to the same stone, etc. – might work out.