Here's more stuff:
1. Haunted Door farming guide:
Go to Gendarran Fields, Brigantine Waypoint. From there, go north toward the hill. There are usually a group of people who farms the doors, just follow them. Tips on farming: focus on using AoE skills and interact with bags. The Haunted Doors are used to get kills for the Halloween Hunting achievement and getting Trick or Treat bags for the achievement.
2. For those who are looking for the special Halloween Weapon Skins(Greatsaw anyone?) if you've opened some Black Lion Chests and got nothing, you can use items from the BLC to create a Mad King's Chest. Go to the Mystic Forge(middle of Lion's Arch) and put in 1 Candy Corn, 6 Mystery Tonics(from BLC), 1 Boost(from BLC) and 1 Boost in the other slot. Mad King's Chest doesn't require any key to open.
That's it for now, I'll post more later.