This achievement is awarded for successfully completing the Dread Pumpkin Quest.
Master or Journeyman mode.
Credit : https://steamcommunity.com/sharedfiles/filedetails/?id=95865...
For the Dread Pumpkin Quest you need to wear the following:
Cloak (taken from the Wraith, Passage)
Hat (Music Room)
Mask (combine the two parts first)
1st part: Suit of Armour, Grand Hallway.
2nd part: Lakmir's Inner Sanctum.
and have the Broom in your inventory (found in the Mirror Room).
The other items you need for the quest are:
Hooked Blade (Strong Room)
Red Candle (Library).
White Candle (Library).
White Candle (Laboratory).
3 Pumpkins, located at:
Well, in the bucket.
Laboratory, under the leftmost grate.
Store Room, under the burlap cover.
5 skulls (these you can find almost everywhere).
To complete the Dread Pumpkin Quest follow these steps:
Go to Landing #3, North Tower, and speak on the door for it to open.
Enter, and go through the mirror to the Pumpkin Patch.
Place the skulls on the outer circles.
Place the 3 pumpkins on the inner circles.
Carve the pumpkins with the hooked blade.
Put a candle in each pumpkin.
Light the pumpkins.