This is a semi-access quest to unlock the different levels of the dungeon. At least one person in the group will need to have completed, or be actively completing, this quest in order for the group to access the second floor and basement. Furthermore, this quest is necessary in order to complete most of the quests in the dungeon since many of the examined-quests are found on the second level and basement.
If this quest has been completed once then all levels of the dungeon will be unlocked; there is no need to complete this quest a second time to access the second floor or dungeon.
Alexa will send you to the Game Room at ( 26, 0, 51 ) /waypoint 26, 0, 51 to find a note left by the castle's architect. Start examining all possible objects in the room until you find the correct one with a hastily scrawled note stashed in it.
Examine the note. It will instruct you to interact with the wall-sconce at ( 22, -0, 67 ) /waypoint 21.71, -0.07, 67.27, opening a secret passage.
Take the secret passage upstairs to Elise's Bedroom. Click the book on the nightstand at ( 46, 13, 85 ) /waypoint 46, 13, 85. This will make Elise spawn on the middle walkway of the ramparts, important for later on.
Travel up the stairs from Elise's Bedroom and exit from either doorway onto the ramparts. Alexa will re-appear, depending on which exit you took, at either ( 61, 31, 45 ) /waypoint 61, 31, 45 or ( 8, 30, 82 ) /waypoint 8, 30, 82. Speak with her to receive the quest.
If you did not already do so, read Elise's Diary back in the southwest tower to spawn Elise on the roof.
Go back up the stairs and turn onto the middle-rampart-walkway. Kill Elise Everling at ( -2, 30, -25 ) /waypoint -2, 30, -25.
Backtrack and continue clockwise around to the east tower. Go down the stairs to the bedroom and kill Jenni Everling at ( -70, 13, -5 ) /waypoint -70, 13, -5.
Head back up the stairs and continue to the southeast tower, at ( -54, 23, 87 ) /waypoint -54, 23, 87. Once you are there, without stopping, descend through Deirdre's Bedroom into the basement below and kill Deirdre Everling at ( -46, 0, 80 ) /waypoint -46, 0, 80. After Deirdre is killed, interacting with the wall-sconce at the end of the nearby hallway will open a secret door similar to the one used back in Sheila's basement. This door will take you back to the first level of the dungeon.
Archfiend Izzoroth will spawn in Deirdre's Bedroom as soon as the first player enters it. He won't aggro immediately, but nonetheless move quickly down to the basement. Although an epic-boss, Archfiend Izzoroth can still be killed by a small group or soloed by a self-mentored player since he is static and has no ranged abilities.
Your journal should now read: I need to figure out what this key goes to. Enter the Quarters of Lord Everling at ( 18, 14, -52 ) /waypoint 18, 14, -52 and examine the book on the pedestal This will spawn Guard Captain Ga'vin - kill him. Then, right-click the stand to the right of the bookcase ans select 'use'. You must right-click as left-clicking causes the character to just inspect the stand. If done correctly, the bookcase will swing open revealing the entrance to the bottom level of the dungeon.
Proceed down the steps, interact with the seemingly dead-end wall, and go speak with Alexa at ( -39, -13, 42 ) /waypoint -39, -13, 42.
Backtrack to a wall sconce at ( -5, -14, -23 ) /waypoint -5, -14, -23 and examine it. This will unlock a secret room to your immediate south. Enter and examine with the scroll on the desk at ( -12, -14, -12 ) /waypoint -12, -14, -12, which enables you to interact with objects found in the basement.
Exit the secret room and use a wall-stone at ( -21, -13, -22 ) /waypoint -21, -13, -22. Go through and confront Alexa at ( -19, -13, 8 ) /waypoint -19, -13, 8. Upon her death, the quest will complete.