This item is one I've used in games for almost twenty years. I remember an illustration of a magic-worker surrounded by streamers of incense, gazing intently into a mirror that was part of a box; I think I saw it in one of those 80s encyclopedias of the Occult which used to clutter the shelves of Waldenbooks and B. Dalton back in the day. In any case, the image stayed with me and I used it as inspiration for a fortune-teller my players visited in a marketplace. Since I portrayed a lot of fortune-tellers as shifty con-artists, a couple of players decided it was the box itself that was magical. I came up with the details of the potential magic item, but never needed it as more profitable larcenies occupied the group.