Icosahedron

The Icosahedron is a twenty-sided object of immense magical power; those that obtain it are granted one of their innermost desires... whether or not they are truly aware of them or not. These desires can be "interpreted" in many different ways by the Icosahedron, and not always in a way that's beneficial to the owner. Given its chaotic nature and tendency to teleport away when its job is finished, it should be no surprise that the Icosahedron was created by Rios.

Perhaps the most infamous instance of the Icosahedron visiting a mortal was the case of Xalthar, the First Necromancer.