After all the staff positions are filled in the Hoarfrost Castle plugin for the Elder Scrolls IV: Oblivion and Grand Designs updates, you accompany Ignatius to his room to get Furius Hoarfrost's journal.
Requiem for the Reluctant
"Ignatius revealed that the journal of the original Master of Hoarfrost Castle - Master Furius Hoarfrost - had been found in the keep during its restoration. He says he believes it holds answers to the mysteries surrounding the haunting of the castle, and wants to show it to me. He has been keeping it in his chambers in the sleeping quarters."
Accompany Ignatius back to his room. When he is there, speak to him. He begins looking for the journal, then is interrupted, saying he can hear Captain Palenix who sounds troubled.
Captain Palenix appears and tells you that there are undead in the Castle. The have come in through a secret door in the Master Bedroom - and the undead include his father. He asks you to come with him.
"Ignatius was about to show me Master Furius Hoarfrost's journal when Captain Palenix burst in and informed us that some undead beasts have come up through the secret passage in my master bedroom to attack the keep! He and the guardsmen drove them back, but he dares not spare the men from their guard duty to pursue them into the caverns beneath the keep. Palenix has joined with me, and together we will destroy the revenants ourselves."
Go to the Master Bedroom and activate the Strange Candle to the left of the fireplace. A door opens in the wall (there is another Strange Candle on the other side to open it from that side) leading to the trapdoor to the Hoarfrost Castle Caverns.
Enter the Caverns. There are two Zombies here; kill them both. Palenix fortunately cannot die. Now go through to the Sanctuary, and kill the four Zombies there. After they are all dead, Palenix approaches you.
"Captain Palenix and I have destroyed the zombies in the caverns beneath Hoarfrost Keep, although 'destroyed' may not be the right word, if the Captain's fears prove true. He swears that these revenants are the remains of his - and the other guards' - parents; that they have returned to haunt us all. Palenix wants to return to Ignatius with me to report what happened. If this journal Ignatius found does have answers to the mystery of this 'haunting', then reading it would be a good next step, in any case."
Return to the Castle and speak to Ignatius. He gives you the Journal of Furius Hoarfrost and asks you to read the section he has marked. Shortly after reading it, you log will update again.
"According to Furius Hoarfrost's journal, he tried to petition the god Arkay to preserve his family and retainers from harm at the hands of the nearby hostile Lords at the time. He created an item he called a 'Conduit' to help his plea reach the gods - only it was not Arkay who responded, but the Daedric Prince Meridia; incensed at the way Furius worded his petition. Meridia cursed him, his family and all his retainers to an eternity of undeath: haunting Hoarfrost Castle. I should discuss this with Ignatius."
Speak to Ignatius again. He suggests you speak to the Captain, as he was one of the children in the Castle at the time.
"Ignatius believes that the key to lifting the curse that binds the previous occupants of Hoarfrost Castle to their haunting of the place lies with the 'Conduit' described by Furius Hoarfrost in his journal. The Conduit is apparently hidden in a place Furius called the 'Inverted Cathedral', but Ignatius doesn't know what or where that might be. He recommended asking Captain Palenix - who was a child at the castle at the time the journal was written - if he has any ideas."
"Captain Palenix told me of how - as a child - he saw Furius Hoarfrost sneaking from the castle, and followed him to a ruin which sounds like it fits the name of the 'Inverted Cathedral'. This was on the day that the occupants of the castle - save for the children - were cursed with undeath, so it sounds like it is indeed the hiding place mentioned in Furius' journal. Palenix showed me on my map where the ruin is located; in the mountains north of Hoarfrost Castle."
On the door into the Sealed Cathedral there is another Ethereal Note pinned to the door by a Silver Dagger, apparently from Hoarfrost himself, telling you how you can kill him. "The Conduit lies beyond this door, But I cannot reach it anymore. It is the path to my eternal rest; If I could force myself near it, I would be eternally blessed. If another should find this, then I beseech you: Take the Conduit - and destroy me; quick and true. Take the Conduit, and grasp it tight: It will whisk you away home, faster than flight. There you will kill me; There you will cure me. There you will free me, And drive out my cursed family. Kill me with the Conduit near, And I will be gone forever; have no fear. - FH"
When you cast the spell for the first time, you are taken to the Hoarfrost Castle Secret Chambers where the Hoarfrost Lich is. You have to destroy it again.
Once you have defeated Furius Hoarfrost, your log updates.
"Furius Hoarfrost, in his lich form, is dead once more. There was an occasion before now when I thought him dead and gone, of course. Perhaps I should speak with Ignatius to see if he has any idea how we can be sure that the haunting of the castle is over."
Go through the door to the Master Bedroom. Activate the Movable Pillar to the left of the door which opens up a secret door into the Master Bedroom. Go and speak to Ignatius. He asks you to speak to Prior Faric who will check to see the curse has been finally lifted. The Prior confirms this, so go back and tell Ignatius. This completes this quest and the entire Hoarfrost Castle quest series.
These are the rewards you get from completing the various stages required to rebuild and reequip Hoarfrost Castle.
You will get a weekly tithe of Gold added to the Moneybox in the Master Bedroom of 200 multiplied by your level.
Vilene sells items, mostly food and drink and is also a merchant with 1,200 Gold.
Bodean will repair items, and is a merchant with 1,200 Gold. He mostly sells weapons and armour
Estirdalin will recharge and enchant items and allow the creation of spells during normal working hours, and is also a merchant with 1,200 Gold who buys and sells potions, ingredients and alchemical apparatus.
Faric will heal you anytime requested. He has also blessed the Chapel.
The Hoarfrost Castle Chapel
Unlike the normal chapels, the Hoarfrost Chapel will allow you to pray at it anytime, without requiring you to seek forgiveness as the normal chapels do if your circumstances warrant it.
The Hoarfrost Conduit allows you to cast Hoarfrost Conduit Recall which teleports you to the Hoarfrost Castle Secret Chambers. According to Estirdalin, it also marks your location, so that you are able to teleport back their using the Return Portal in the Secret Chambers. This means that you can teleport from inside a dungeon back to the Castle, deposit loot there, and then return. This ability to easily teleport out of a place to a location where you can store supplies and return back to where you were is actually somewhat overpowered.
Hoarfrost Castle Secret Chambers
These can be reached from the Master Bedroom in Hoarfrost Castle or by casting the Hoarfrost Conduit Recall spell. In the Secret Chambers are a number of Strongboxes as well as several portals. There is a Return Portal, which allows you to return to the last place you cast Hoarfrost Conduit Recall. There are also teleports to Anvil, Bravil, Bruma, Cheydinhal, the Imperial Palace, Chorrol, Kvatch, Leyawin and Skingrad. The Imperial Palace teleport transports you to the Elder Council Chambers, the Kvtach teleport is non-functional and the rest teleport you to that city's castle into its' Great Hall or equivalent.