Hey, so I see we've slipped into the Mask theme. :) I took a look at your PrC, Zaydos, and I like it! It has a great feel to it and some really nifty abilities. Almost simultaneously- and much less expertly, I might add, I was inspired by ideas from Majora's Mask to make a PrC as well (Lord of the Masks). I'm not sure if it fits perfectly here and will leave it up to you whether or not the mask theme makes it Halloween enough.

That said, I do have some mask ideas which are more horror oriented that I wanted to post for the garden.

Sometimes, when darkness plagues the land with great numbers and ferocity, all you can do is fight back. Some have taken this more in stride than others. In an effort to beat back the darkness, some have borrowed the darkness for themselves.

Masks of Monstrosity
If anyone wishes to add to this list, please feel free to do so. I may add more as time goes on.

Mask of the Werewolf:
This mask is made of course, gray fur, cured leather and white bone that gleams like moonlight. The jaw juts forward a few inches forming a brief snout. When it is worn by a creature with the humanoid type it fuses to their face. The creature sprouts course fur over their upper body and grows sharp fangs and claws. The fangs and claws may be used as natural weapons(1d4 slashing for the claws and 1d6 piercing for the bite.). Additionally, the wearer's skin hardens. The creature gains DR 2/silver and Darkvision while the mask is worn. The wearer is overcome by a furious bloodlust while in this form, taking a -2 to AC and all skill checks. Additionally, the wearer cannot sleep with the mask on and may never retreat or use the total defense action or Diplomacy skill, focusing only on offense whenever possible. This mask cannot be removed at night.

Mask of the Undead:
This mask is made of cured leather and carefully carved wood. It appears to be a rotting face with sunken eyes and a missing lower jaw. The skin of the wearer becomes sallow and sickly, and their hair becomes ragged and frayed. The wearer is treated as an undead for the sake of all magical effects and is immune to critical hits. While worn, the mask forces the wearer to move at a shuffling stagger (half speed) and reeks of death, suffering a -3 penalty to all checks involving social interaction, with the exception of intimidate, which is performed at a +2. This mask cannot be removed except in bright light.