Wondrous Item, uncommon
Two steel spheres in an ornate wooden box, one bigger than the other one but each fit into a humanoid hand comfortably. If a creature holds the smaller ball, the creature will feel a gentle tug in the direction of the bigger one, wherever the bigger one may be as long as it is on the same plane of existence. If the bigger ball is on a different plane, the smaller will remain still.
(Based on item listed in A Mission to Thay: Nethwatch Keep)