Only during Halloween:
"When Mad King Thorn shows his pumpkin face around these parts, people tend to start dressing up in costumes...perhaps to hide from the mad monarch. Of course, the question is, what does a hearty adventurer do after getting all dressed up? Well, go partake in the Costume Brawl of course. No, not ball, brawl. Adventurers of all skill levels are welcome at the arena for a brawling good time. Would you like me to escort you to the Costume Brawl?"
- Accept: I am ready to party! Send me to the Costume Brawl.