Cube of Force

From publisher blurb:

The cube of force is one of the most recent additions to the magic items considered to be common. This strange arcane item has continued to creep up in common usage as it becomes used by more and more adventurers and created by more and more wizards as proof of their magical might and crafting prowess. More than six dozen wizards have crafted at least one cube of force in the century since their inception and many have found their way into the arsenals of adventurers while a few more have stayed on their shelf in laboratories.

This supplement has includes:

Creator of the Crystal Ball
History of the Cube of Force
New Magic Items: Sphere of Force, Bridge of Force, Brick of Reinforcing and Force Battlements.