The blackboard of the middle ages
A large steel shield in the form of a sea-shell attributed to Athena, the goddess of civilization, craft wisdom and war.
A Castle or better a fortified tower is floating over the country side and being attacked by goblins (or other monsters, depending on PC strength)
A plague is spreading trough the lands, the plague is actually an old woman carrying a stick. She walks from farm to farm spreading the plague. Can the PCs stop her without getting infected.