Forged long ago for a high-level noble (or Lunar) bureaucrat who served at the Wind Pass permanent trading camp, the silver hemisphere is a fine silver half-globe about the size of half an orange. It is covered with a fine pattern of engraving that blurs vision slightly, but in a pleasant way.
Anything under the silver hemisphere is held down with a strength of 20. Anything attempting to move the hemisphere or anything underneath it must overcome that effective STR. The sphere yields easily, however, to a human hand. This makes it the perfect paperweight in Wind Pass.
Unfortunately the garrison at Wind was slaughtered to the last man by trolls. Over the years the silver hemisphere has changed hands many times. It is of limited usefulness; it can be used to hold down a prisoner, for example, but will yield immediately if the prisoner touches it.
Clever players may be able to think of other ways to use the Silver Hemisphere.