“ Village has a nearby natural substance that comes from the ground and burns well when lit. They use it only locally and try not to let the secret get out.”
“ Near a major city, a mirror image of the place has appeared. This strange double is infested with hostile insectoid humanoids that appear to match the city folk in numbers and armaments. The humans' diviners have determined that the secret of the city's appearance can be found within the double's college of magic, so heroes are needed to explore within this mirror city and discover what has drawn it from its distant realm. There isn't much time to spare, as the bug folk find their mammalian counterparts unnatural and blasphemous, and plan to destroy them.”
“ The PCs are walking along the road, when suddenly a bunch of bandits attacks. The player's dismiss it has just a random encounter, when they find an ornate ring on the leader, obviously out of place with the seemingly poor bandits, who could only afford cheap leather and weapons. This ring has a symbol on it, which, if researched, sets the PCs on a quest. And from then on, the players don't look at random encounters the same way...”