In the middle of an unimportant combat with some bandits a burst of wild magic transforms all of the PCs and their opponents in to random animals and monsters. They retain their intelligence (though not, of course, the ability of speech). They can either carry on the combat in their new forms, panic, or otherwise react how they see best. After about an hour, they return, unharmed, to their normal form.
In the dry steppelands, one of their most valuable exports is the dried sap of the Larthorn tree. These ugly plants are covered with vicious thorns, but the locals harvest the golden droplets that ooze from their bark each Autumn. This sap, once dried, is valued for its medicinal properties and as a spice. Since little gold or silver is found in the hinterland, the dried droplets of sap are often used as currency by the locals.