There are lots to do in the Halloween event in Guild Wars 2, but the primary objective is completing the scavenger hunt known as Shadow of the Mad King. You start by first talking to Magister Tassi in Lion’s Arch (located in the Grand Piazza), who will mail you a Candy-Powered Matter Meter and a Personalized Trick-or-Treat Bag. The Candy-Powered Matter Meter (CPMM) will scan various frequencies at the cost of one Piece of Candy Corn. Candy Corn is sort of the currency for the Halloween Event.
The scavenger hunt takes no time and is a lot of fun for you to figure out yourself. One candy corn is enough to scan each frequency once and if someone uncovers the ghost then it is uncovered for everyone, so you may not even need to use much of your candy corn. You’ll get some candy corn to start with (actually you'll get a Personalized Trick-or-Treat Bag which will contain one plus some random goodies), but let’s do a quick rundown of candy corn sources in case you run out.
The first is you’ll get them from Trick-or-Treat Bags which are random drops out in the world or you can get them by giving costumed children candy (although you’ll lose more candy corn then you make). You can also get Candy Corn from Candy Corn mines and the Trading Post or completing some of the events, like the Lunatic Inquisition. You can also mine them rather frequently in the Labyrinth, assessable from the portals in the Human starting areas.
There are spoilers ahead, although we try to avoid going too in-depth to keep some of the fun of the event alive. If you're wanting to do it without the spoilers, but need a simple hint to get started, look at the hints given on each of the pages that you recover. They explain the locations in the form of a riddle. Each page will give hints on how to locate the others.
You’ll need to collect six memoreis to complete act 1 which rewards Mad Memoires, a back item that is a book.
Mad Memoires I: Boyhood
The first is a freebie, it’s the ghost standing right beside Tassi named Serene. Use your Scan Etheric Field if she’s not already uncovered.
Mad Memoires II: Friendship
You’ll need to go into the sewers for this one, but don’t worry it’s not that difficult. It’s at the lowest part of the sewers where the ship wreck is, you can get there by taking a left and then a right from the above water level entrance near the Trader’s Forum Waypoint and then going down. You’ll want to use the Aqueous scan whenever the water starts turning blood red.
Mad Memoires III: Young Love
This one is really easy. I’ve included a map, but basically go to the stone building in Old Lion’s Arch and use Scan Etheric Field. There are also a few locations nearby that you can scan for some treat bags.
Mad Memoires IV: Deadly Adventure
This one is in Shaemoor in the graveyard outside of Divinity’s Reach. The easiest way to complete it is just go to the location I’ve shown above and use Scan Gaseous Field.
Mad Memoires V: Betrothed
A very easy one, go to the Delanian Waypoint in Kessex Hills and go to the north side of the hill to the north and follow the path. Use Scan Corporeal Field in order to get the next mad memoires.
Mad Memoires VI: Coronation
This one can be difficult and at times you may be able to solo it or you may need some friends. If no one is around and the Champion Spider is up, just wait around for a few other players to come. Go to the Provern Shore waypoint in Gendarran Fields and walk west. There is now a crypt call the Provernic Crypt. It has three parts to it. The first are simple flame and spike traps that you’ll need to dodge roll through. The second is a larger room with spike traps, pressure plates, and boulders. You’ll need to put boulders on the two pressure plates to open the door. In the third room there is a Grand Chest and in a nook in the corner of the room you can Scan Gaseous Field to unveil Faren and get your last part of the scavenger hunt.
Return to Tassi in Lion’s Arch to receive your reward, Mad Memoires, congratulations on completing Act 1! Now continue to to Act 2!