ArenaNet has decided to celebrate Halloween in Guild Wars 2 with a brand new world event called Shadow of the Mad King.

The event goes live today, October 22 and will run until October 31, consisting of four acts. Each of these acts will deliver new dynamic events, and the update as a whole adds new decorations, dungeons, achievements, and a new PvP mode called Costume Brawl. You can check out the event’s official trailer here.

A brief description of the event can be found below:

500 years ago, a tyrannical Krytan king was slain by his own people, those who had suffered greatly during his reign of lunacy. It is said that this king’s body was chopped into pieces, and his spirit was banished to the Underworld, but that he can return to the mortal realm for just one day a year: on Halloween.

Of course, that’s just an old folktale. Isn’t it?

It’s been 250 years since the last alleged sighting of Mad King Thorn’s spirit, and today, Halloween is safely celebrated by children (and merchants) all across Tyria.

But! Strange energies are rising under the autumn moon. Is there perhaps some truth to the old stories? Do you dare to find out what’s really going on?