Many, perhaps most fantasy lands are monarchies, which can be ruled well when the monarch is a clever and able man or woman devoted to his or her people. But what happens when the monarch is ill, or is tyrannically cruel, or a young child, or is otherwise blatantly unfit to rule? How can he or she be dealt with without risking civil war as powerful nobles fight for the crown?
One of the current political paradigms of the Cosmic Era.
The plague of the Petroleum Era, the true bane of organized government
Nearly every primitive culture has had rituals and celebrations to guarantee the proper passage of the seasons and to ensure the fertility of crops and animals. Oversight of these ceremonies was generally the provenance of local kings or priests.
Suppose that the adventurers dispatch one of these fellows. The local peasants may become hysterical, fearing famine and death will stalk the land. Alternatively, they may want one of the new heroes to become king. For a while, this can be a good thing, but the first time that the crops fail, the superstitious locals will want to sacrifice their new leader.