Impossible Cube
Metal made from ore that has visited at least 7 planes
At a glance this hand-sized item appears to be a metal framework in the simple shape of a cube, but when looked at more closely it becomes clear that the geometry of the framework is impossible with absurd angles, preposterous twists, and endpoints. Any attempt to follow the various lines and compositions to their conclusion is frustrating at best and truly maddening at worst.
When a creature with an Intelligence score of 6 or higher sees the cube for the first time it makes a DC 10 Wisdom saving throw or becomes compelled to study the cube further. When a creature first studies the cube, it makes a DC 15 Wisdom saving throw or suffers from the Terrorized short-term mental stress effect and a compulsion to study the cube even further. A creature that fails this saving throw by 5 or more instead suffers from the Distorted Perceptions long-term mental stress effect. Any further inspection of the cube has no additional effect.