There are many items like this in most Fantasy RPG's out there, but this one was a fairly early example, so I have decided to make my entry about it, rather than every variation (including the Spell Magic Jar, which has similar capabilities). When the first being to touch this item loses their life or body, their essence is transferred into the amulet. Then, if anyone puts on the amulet they can try to wrest control over the body to use as their own. This particular example of such a device also has a power suggestion placed upon it to compel the unfortunate victim to put the amulet on. The reason I like these kinds of items for my own campaigns has to do with the fun that can come from switching bodies, as this can really be a memorable way to get players to understand what other players characters are about. This is also a common trope in Science fiction and fantasy novels, for good reason! Consider carefully all the issues that can come from a device like this in play in your campaign, however. One way to mitigate losing an entire party to such a device would be to either have some power being protecting or looking out for said item, or the life force contained in it. Another would be to have the life force be from very ancient times, thus giving the force a very difficult time integrating, making it much easier to find their former friends and force a change. Also consider some ways to switch minds back outside the amulet (mysterious pools in the local dungeons, some miracle working old hag in the nearby forest, or the like.) so that the players don't get disheartened when the find themselves without a body.