Go to the basement under Elise's Bedroom. Billy should spawn as you enter. Kill him. ( 49, 0, 75 ) /waypoint 49, 0, 75
Go to the The Game Room at ( 32, 0, 59 ) /waypoint 32, 0, 59 and walk into the room, Billy will now auto-spawn when someone is on this step of the quest.
Go to the the Chapel at ( -36, 0, 53 ) /waypoint -36, 0, 53. Again Billy auto-spawns when you walk into the room now.
Go to the Library at ( -27, 14, 59 ) /waypoint -27, 14, 59. Read a book in the secret area behind the bookcase. It's the book leaning against the coffin at ( -23, 13, 29 ) /waypoint -23, 13, 29. It's written by Everling and he says, "the dolls I need always come to me in the courtyard".
Go down to the center of the main courtyard by the entrance. An NPC version of Billy will spawn automatically. Hail him. The dialogue gives you two options, either give him 5g or yell at him. Give him gold.
Go to the jail and hail the froglok ghoul assassin at ( -24, 0, 29 ) /waypoint -24, 0, 29. He tells you to get something to soothe his soul.
Go to the Library and read the directions on a scroll at ( -22, 13, 31 ) /waypoint -22, 13, 31 in the hidden area; on the standing bowl not the desk. Kill the following monsters:
21 Nyth dolls. There are only ~30 dolls in the castle and they do not respawn, so make sure you don’t kill them before you need them.
There are four Nyth doll encounters in the zone; see monster page for details.
Swine Lord in the stables at ( -18, 0, -30 ) /waypoint -17.5, 0.00, -30.00.
If Swine Lord isn't up then kill his placeholders and wait for the respawn.
Go back to the froglok assassin and speak to him.
He despawns at the end of quest conversation. If in a group, have everyone speak to him at the same time. If for some reason someone was unable to speak to him before he desapwns, his respawn is ~10 minutes.
If you fail to kill Everling and respawn at the entrance, you will not be able to get back to him as the entrance to his laboratory locks. You will have to wait until you can enter the zone again to finish the quest.