The PCs traveling along the road/path/trail begin to hear a low droning sound. As they approach they find their path obstructed by hundred of thousands of droning insects. Locusts swarm though the air, feasting on the grass and plants. Passage will be slowed, but the insects pose no threat to the party, aside from being crunchy and disgusting underfoot, climbing into pouches and eating exposed food goods.
Game Cliche 2.
Upon learning about "the five ancient jewels" or "the nine legendary icons" or whatever, you can be quite confident that Saving the World will require you to go out and find every last one of them.