I'm suggesting for Halloween to simply enable aggressive mobs in the main world and have them at a higher spawn rate than vanilla minecraft. Simple enough, but I know some of you would think "Wouldn't this create problems?" Well yes, but that's why I suggest phy should make an announcement 48 hours prior, and another 2 hours prior to the event, and then a spam of shouts ingame prior to restarting the server upon enabling aggressive mob spawning. If possible there could even be a message upon entering the game warning you. And heck, while I'm suggesting aggressive mobs, why not suggest they have pumpkins on their heads too for the spirit of Halloween? If this is possible, DO IT. I say possible because it probably requires a bit of... "magic."