"The wind-driven snow parts for the barest of seconds, revealing a glimpse of refuge from the deadly storm. It’s a massive sapphire pyramid. Yet you know of nothing like it in this area…"
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.