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.
A simple flag, faded by time and sun, tattered and worn by untold years flying from the pole of a bannerman, passing hands from officer to officer, from one generation to another. It is a humble symbol of great importance, and greater inspiration to those who see it. Soldiers become heros filled with espirit de corps, enemies loose their nerve and fire. It is not an enchanted item, but a powerful item still...