Hi all, I've decided to come up with an adventure that is tailored to fit everyone's favorite October Holiday.
Basically, I've decided what I want to try to do, and desire feedback on what others think.
The PC's, who have been exploring a "dungeon," find a strange room filled with what appear to be costumes. There is a costume for each PC, each looking like a different monster. These costumes, when inspected, seem to hold powerful magic (an incentive to make the characters want to put them on).
once donned, these costumes "transform" the players into the creature that they have put on. For example, the werewolf costume would give the PC that put it on claws and fangs, allowing new forms of attacks. A half-dragon costume would grant a breath weapon to the player.
the downside is this: once the suits are on, the PC's can't take them off until they find the person who created them. To get there, they will have to travel through a well-populated town. In fact, its a town where adventurers commonly gather in search of adventure or work.
because they look like the monsters, these other adventurers will attack them on sight, and they will be forced to either flee or kill people they consider allies.
that's what I have worked out so far, so please, let me know what you think. If you have suggestions for changes or additions, I'd welcome your ideas.
Looks pretty solid. If you're shooting for a creepy feel to it, I'd also advise taking a look at Heroes of Horror if you can get your paws on it. It's got some good tips for upping the atmospheric scare factor.
Heroes of Horror, huh? i've seen that book around but never actually seriously looked at it. I may have to check it out within the next week or so.
Thanks for the advice 
It might help if you described the costumes as magical armor (and have them take up that slot). Most costumes would probably be cloth armor (maybe masterwork), but you could have something like a troll costume count as hide armor, or a dragon costume count as scale armor - and have that be the criteria for deciding which costume is *for* which PCs.
Your players may hesitate to don magical costumes - but if they find high-powered magical armor, even if it looks a bit rediculous, they might be more interested. Particularly if they think they would have the option to use transfer enchantment to move it onto more normal-looking armor later.
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You may want to also keep in mind that in all likelihood, your players will not all put on the costumes at the same time. One daring, or careless adventurer would probably put one on first, while the other wait to see what effects the costumes would have. When they see their friend transformed into a monster - and unable to transform back, they may be hesitant to follow in his footsteps.
Also, consider what you will do if the players take a short rest before deciding about the costumes, and attempt to identify them. If they are artifacts, that's a whole other bag of problems, but assuming they are simply magical items, and you have a half-decent arcanist on the team, the adventurers should probably be able to get a ltitle bit of warning about what the costumes do.
You may want to also keep in mind that in all likelihood, your players will not all put on the costumes at the same time. One daring, or careless adventurer would probably put one on first, while the other wait to see what effects the costumes would have. When they see their friend transformed into a monster - and unable to transform back, they may be hesitant to follow in his footsteps.
Also, consider what you will do if the players take a short rest before deciding about the costumes, and attempt to identify them. If they are artifacts, that's a whole other bag of problems, but assuming they are simply magical items, and you have a half-decent arcanist on the team, the adventurers should probably be able to get a ltitle bit of warning about what the costumes do.
What if to take care of that problem, I did something like one of the following:
1. as soon as the costume/ armor is touched, it magically forces itself onto the adventurer, which triggers the other cursed suits to put themselves onto their respective PC's
2. The costume/ armor won't do anything until they leave the "dungeon." However when they leave, the costume's hidden magical properties (the transformations) take effect
those are just quick ideas I came up with during lunch... but I'd like to know if anyone has either better ideas or just opionions on the two I came up with
I like the idea. I would think about allowing the players to come up with some non-lethal forms of combat - they might not want to kill anyone, so it might be worthwhile reminding them of the temporary/knock out damage rules.
When the characters come out of the dungon the players come across a witchfinder hanging the local witch. If the players save the witch she will explain the nature of the curse and maybe give them a helpful item (wand/rod of paralysis or something).
They players will also have made enemies of the local (overzealous) religious authorities unless they keep their mouths shut.
good goody two-shoes might have issues helping the witch. maybe her house is under attack by rioters and the group is misinformed on her identity?