and the rest of the guide ...
Also tied to the event is the amazing costume 
Exquisite Costume Set: "The Lich King", new wands such as 
Hallowed Wand - Slime, new battle pets 
Widget the Departed and 
Cursed Birman, and several pug disguises (
"Mad Alchemist" Costume, 
"Lil' Starlet" Costume, 
"Yipp-Saron" Costume). We'll update this guide when the event goes live with more details on the new items, including source and location.
There are costs listed on Chinese Battle.net but they sound a bit high and may not be the same for US/EU realms.
In addition, 
Little Wickerman is now classified as a toy to fit into your brand-new Toy Box!
Tricky Treats Loot
Since 2011, gone are the days of trick-or-treating hourly for a chance at an extremely rare mask or a rare vanity item. Instead, the event has been streamlined into a vendor and daily system, very similar to Noblegarden. One vanity pet, 
Feline Familiar, makes its appearance here on a vendor, for example; meanwhile, old favorites, such as 
Sinister Squashling are purchasable. There's also 
Creepy Crate from a short questline and Little Wickerman from vendors which is a fun campfire.
Tricky treats are obtained through dailies and the pumpkins spread throughout inns on the map. You will get two treats for every inn you visit as a one-time only reward, along with a potential for a mask, wand, or other fun holiday item. You then spend the tricky treats at vendors outside of your capital cities.
Vendors and quest-givers are located at special holiday hubs outside of Stormwind and Undercity.
Vendor Items
Hallowed Wands
Consumables
Pets and Mounts
Misc
Masks
Battle Pets
Hallow's End has five festive battle pets, four of which can be caged and sold on the AH:
In 2014, there are two more pets:
There are also three 
Perky Pug disguises: "Mad Alchemist" Costume, "Lil' Starlet" Costume, "Yipp-Saron" Costume.
Candy
Those candies you get from trick-or-treating have changed several times over WoW's history. They used to be buffs, offering amounts of stacking stats such as spell power with every consumption. However, that's changed and they now provide only visual effects.
You can also purchase Hallow's End Pumpkin Treat from Katrina Shimmerstar and Rachelle Gothena. This candy has 4 possible effects:
-
Hallow's End Candy: Large and orange, 5% chance to increase time between attacks by 25% and reduce movement speed by 30%
-
-
-
Toys
Little Wickerman is now classified as a Toy, which means you can put it in your Toy Box collection. This makes the toy account-wide and more importantly, frees up a bag slot!
Wands
Unlike many other Hallow's End consumables, wands do not require the event to be active in order to use them, so you can have fun disguises all year long.
Five more have been added in 2014:
Masks
2011 added many new masks. First and foremost for the two playable races added in Cataclysm:
Sadly there seem to be no pandaren masks. This brings the amount of masks for playable races up to 24.
In addition to the playable race masks, there are also four sets based on non-playable races; these masks have buffs. Because they function as buffs, they cost more to purchase and are probably meant items for the player who has nearly everything as a currency sink.
New Buffs
Two powerful buffs are tied to the Wickerman Festival. Every four hours there is a city-wide announcement and then 10 minutes later, Sylvanas or Genn buffs nearby players.
Decree of the Dark Lady is granted to nearby players upon observing an RP event in which Sylvanas watches the burning of the Wickerman and declares it to be a sign of the strength of the Forsaken. It lasts an hour and persists through death. Level 1-79 players receive a non-mastery version, Decree of the Dark Lady.
Greymane's Resolve works in the same way for Alliance players--Genn Greymane watches the burning of the Wickerman and celebrates the resilience of the Worgen. It lasts an hour and persists through death. Level 1-79 players receive a non-mastery version, Greymane's Resolve.
You can also obtain 
Unburdened/
Grim Visage and is easily gotten--just use the ashes on the ignited Wickerman bonfire outside Stormwind or Undercity. The experience bonus works on mob kills only, and the reputation bonus works on everything. The reputation bonus also stacks with other bonuses like 
Diplomacy and 
Mr. Popularity.
If the ashes are not available, wait for someone to finish 
A Time to Build Up or an NPC to rekindle it.
Treats and Goodies!
Acquiring Items
There are three main ways players can acquire quirky seasonal items during the Hallow's End festival:
Candy Buckets, 
Crudely Wrapped Gift, and the Headless Horseman.
Candy Buckets (in the shape of pumpkins) are nearby the innkeepers of friendly inns. Instead of talking to an innkeeper each hour for a Treat Bag or a Trick disguise as in the past, looting each pumpkin will reward players with a 
Handful of Treats (and sometimes a temporary character disguise, like the Trick debuff--do keep in mind this silence/pacifies you). This contains 1-3 
Tricky Treat, some candy, and other vanity items. If you don't get lucky with finding rare items in your candy bags, don't worry--the Tricky Treat can be used to purchase them instead. This system takes the RNG component out of the holiday that many had complained about.
(As in past years, there's also an
Apple Bob nearby, which gives players
Bobbing Apple.)
A
Crudely Wrapped Gift can be obtained after protecting a low level Alliance (Goldshire, Kharanos, or Azure Watch) or Horde (Razor Hill, Falconwing Square, or Brill) village from the
Shade of the Horseman (see
Quests section below). The matrons located in these villages will ask for your aid in putting out fires in local buildings. When the
Shade of the Horseman has been defeated, a large
Jack-o-Lantern will appear on the ground that gives the quest
Smash the Pumpkin (Alliance) which can be turned in at the nearby Matron. The Matron will reward you with a sum of gold and a
Crudely Wrapped Gift, which can contain candy, masks, or even riding brooms!
The
Headless Horseman is a level 90 boss that players can queue up for using the Dungeon Finder tool. The boss will then spawn in the Graveyard of
Scarlet Monastery. This encounter can be completed easily by a decently-geared 5-man of level 90 players. For more information check out the
section below!
Since 2014 offers new items, we wanted to break down how many Tricky Treat you'll need to get everything you want. Note: this section may be updated when we can confirm sources and costs for all new 2014 items.
-
New to 2014 loot: if you want to get the two new battle pets and 5 new wands, it will cost you 310
Tricky Treat.
-
All the battle pets: four battle pets will cost you 600
Tricky Treat.
-
-
Items needed for all the Hallow's End achievements: You'll need an additional 48 for
A Mask for All Occasions, bringing it to around ~371.
-
You can acquire 4-6 Tricky Treat inside 
Loot-Filled Pumpkin, which can be run daily. Averaging 5 Tricky Treat in the bag, you can get ~75 with 15 days.
You can complete several daily quests, listed below, for 12 Tricky Treat daily or 156 with 15 days.
You can acquire 1-3 Tricky Treat inside Handful of Treats which is a reward from every single Candy Bucket. Each faction has over 120 Candy Buckets, so assuming 2 Tricky Treat, you will get +240 Tricky Treat from looting all the buckets.
This isn't enough to buy every single item for fun, but if you are just doing this on one character, you can comfortably get all the items needed for 
Hallowed Be Thy Name--also keep in mind several items can be obtained through alternate means, like the Headless Horseman.
You can also run the event on alts for the remaining battle pets and Toy, as these items are account-wide when learned.
Candy Buckets
Seasonal, pumpkin-shaped Candy Buckets are located inside every inn, near the Innkeeper. Each bucket offers a one-time quest that can be completed and rewards a small sum of gold and a
Handful of Treats, which contains 1-3
Tricky Treat and then has a chance to have other items such as masks and snacks. These snacks include
Pyroblast Cinnamon Ball,
G.N.E.R.D.S.,
Chewy Fel Taffy, and
Soothing Spearmint Candy.
You can also get Trick debuffs: Bat, Cat, Frog, Mini-Diablo, Snake and Wisp.
Visiting all friendly inn buckets on continent will reward an achievement. There is one for Pandaria too.
