Oooh, wow. Five 'don't do' is a LOT for a prompt fest. That leads right into the whole "they ruined my prompt" that I've seen too many times over the years. Allowing a list of don'ts makes it feel more gift-like than prompt-like. :| If you go that route, maybe include the option for a participant to select/create their own prompt as well. That way there's definitely a chance for everyone to do something they like. (For example, if every prompt submitted says "No non-slash Draco side pairings", that's every prompt I won't do. The option to do an 'own prompt' there would be very helpful.)