“ Somewhere along the line, someone very powerful lost their marbles. Literally. Possessing a marble allows incredible clarity of thought about a particular related subject.”
“ A casual remark by one of the party about something met on a previous adventure leads to a summons to and grilling by the Mages' Guild (or equivalent), probably resulting in an expedition back to that area to recover the things for study by the Guild. The party's presence will be 'requested' for this expedition.”
“ A culture believes that souls are recycled. One child gets half of a soul, another child gets the other half. However, this means that with each passing generation, the amount of soul in the child will become less and less (Through division)until their culture will die in the future because of their soulless offspring.”