“ A large river that is continuously covered in a thick layer of fog. There will be either a rope ferry to get across or possibly a boat that is rowed across by worshippers of the water elementals. It is very thick fog to the point where it even muffles voices even at close range and visibility even beyond a foot is almost impossible.”
“ A caravan is traveling through the desert. The party is hired to capture a man who is in the caravan, and it must be done quietly, so that nobody else knows. They are given the man's name, and the fact that he is a mage, but no other information about him. The catch is that the caravan consists of ten wagons, with at least thirty or forty guards.”
“ 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).”