The Diadem:

The wielder of the Diadem may perform an Extremely Hard Quest to acquire any of the three gems that fit within it. For each gem installed into the Diadem, it will grow in power, but so will it's downsides. Each time a gem is found, and installed, the difficulty of the next quest increases. No progress can be gained on the quest unless the Diadem is equipped. Current Effects: Gain slightly increased chances of success on all attempts to increase stability. However, whenever a level of stability is lost, there is a 5% chance you will lose two levels instead. This may only occur once per session.