Worst derp for me was a run with my FC in story mode Haukke Manor. We were fighting the arhiman right before the final boss, and my Ifrit-Egi followed it when it ran away into the room, triggering the boss fight. The bard and I, being ranged, were not close enough to make it before it was closed off. Our paladin tank and conjurer healer successfully two-manned the fight. I still get teased about that.