Local insane asylum will sure love their patients learning to sing a little more in tune.
Item #291:
Minor Artifact: The Time Keeper
An intricate, small mechanical pocket watch that can turn back time, but can only turn back however many seconds you have personally spent winding the clock.
The clock, in effect, "stores" down the person's time inside it, and then rolls it back all at once. The user can't choose how many seconds they will release and can only use all of its power at once - before having to wind it again.
Additionally, while winding down the clock, you become utterly entranced and can take no other action, and do not recall the experience of winding it - including how many seconds you have spent winding it.
The clock entrances the wearer so much, that you can't stop winding it down unless you succeed in a DC XX Will save, or are physically removed from the watch. The user can re-attempt the test each hour.
These properties mean that accurately keeping track of how many seconds, hours, days, weeks, months or even years one has spent down winding the watch is an especially challenging prospect.
The user needs to succeed in a DC YY Int check before winding down the clock to be able to keep track of time while under the effects of the trance, in addition to the Will save to break it.
A DC ZZ Int check is also required to recall how much time, in total, the user has spent winding the clock.
While winding it, the watch provides no magical sustenance or protection from aging whatsoever to the wearer, and many have died while trying to use its magical properties. It takes a specially strong-willed and intelligent individual to be able to make full use of its abilities.
Its last known location was at the hands(or claws) of a particularly vicious Great Wyrm Red Dragon, who seemingly always knew ahead of time of all attempts to end its reign of terror.
(I got a bit carried away with this one, as you can see)