Imagine a person wearing a cloak of invisibility flying a flying beast (e.g. winged horse, gryphon) which was also wearing a cloak of invisibility.
Small identical wooden or metal discs with a strange pattern engraved upon them (do not appear to be coinage). The discs can be found all over the continent; a farmer typically overturns several dozen when ploughing a field. Though they are unnaturally hard to break, they have no known use and are widely used as good-luck charms: almost all households would have them on the doors and on mantle pieces; many people carry one or more on them, bound on to a belt, necklace or sewn on to their clothes.
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.