A fun fey boss for level 6s

I'm planning a fey carnival theme one shot for my players where they give their names at the start and then all of the games are trying to win enough prizes to get them back.

I was thinking of using the centaur warden and reskinning it for the final encounter (summoning a magical clown car for the charge attack etc) but it's not quite tricksy enough for what I'm after. Does anybody have any better ideas or should I just homebrew add in some more features for him?