Weighted Companion Cube (3.5e Equipment)
From D&D Wiki
The cube in the center of the room is about three feet by three feet. The corners are tipped grey. In the center of the cube is a large pink heart. The heart glows faintly. It appears the same on the other five faces. Upon looking at it, you immediately feel somewhat attatched to it. The Cube looks heavy.
 The Cube
Some say that the cube was created by an ancient Wizard construct, driven mad by lonliness- And the feeling is infectious. Anything with an intelligence score -even constructs and undead- viewing the cube for the first time must make a DC 20 Will Save or become infatuated with it. Another check must be made each hour at a cumulative -1 penalty. On a failed save, the victim will attempt to spend as much of their time with the cube as possible, by any means nessescary. On the upside, carrying the cube gives the wielder concealment due to its size. The cube can not be broken by normal means. Think of it as infinite Damage Reduction with a single weakness: An Aperture Magic Emergency Intelligence Incinerator or 'Furnace'. It can also be sold, by anyone able to withstand its charm. The cube weighs somewhere anywhere between 1 and 30 kg. (Roll 1d30 to find out).
Prereqs: Create Wonderous Item, Charm Person, (Spell for the invulnerability effect?)
Cost to Create: To be Determined