“ The player characters, experienced and somewhat well known, hear rumors and travelers' tales about a distant area being overrun by dragons (or other terrifying monstrosities). The locals have sent them a message, begging for heroic aid.
When they investigate, they discover that nothing of the sort is going on. It turns out that a group of thieves wanted them out of the way so that they could rob them (or someone who would normally receive their protection).”
“ 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 world where most people know a few cantrips and even non-magical people can help to cast spells. Which is just as well because the big spells can only be cast with the help of large numbers of people.Most large spells tend to protect borders and stop earthquakes as they can be done legally, but there are those willing to cast bad large spells s well.A major part of law enforcement in this world is preventing evil magic.”