Online:Breaking the Shackle

Quick Walkthrough
# Talk to Vanus Galerion.
# Find the Great Shackle's power source.
# Reverse the energy flow in the magicka conduits.
# (Optional) Along the way, save Sage Tirora and Treva and they will help you later on.
# Enter the Great Mooring.
# Defend Vanus Galerion.
# Return to the Hollow City.
# Enter the Mages Guild District.
# Talk to Vanus Galerion.

Detailed Walkthrough
Entering the Shackle
After rescuing Vanus Galerion from the Black Forge, he will still want to complete his initial goal, breaking the Great Shackle to end the Planemeld. But he'd like your help with his second attempt.

:"The time has come. The Great Shackle must be destroyed."
:What can I do to help?
:"Stay close and follow my every command. Taking down the Great Shackle—the primary conduit for the Planemeld—requires precision and the careful application of destructive spells. As it so happens, I am a master of destructive spells."
:'''Let's go destroy the Great Shackle.

Before you leave, Vanus will ask if you have questions, which must be asked before he will begin.

:"This won't be easy. Is there anything else you want to ask me before we move out?"
::What else can you tell me about the Great Shackle?
:::"What can I tell you that isn't obvious? The Great Shackle is the ultimate version of Molag Bal's Dark Anchors, a massive weapon capable of completing the Planemeld of its own accord. It would be a fascinating device if it wasn't so terrifying."
::Is there a plan you want to share with me?
:::"They wanted to use my energy to power the Shackle. That indicates to me that the Shackle utilizes some form of energy.  Disrupting that flow of energy may be key to destroying the Great Shackle. I'll know more once we get inside."
:Then let's get moving. (Option appears once both questions have been asked.)

He will then begin to walk across the bridge. As you follow him, Vanus will explain the effect the Shackle has on Nirn.
thumb|left|"A barrier spell on the door? How pedestrian! Give me a moment and I'll open the way."
:Vanus Galerion: "The Shackle sends metaphysical chains of energy across the planar chaos to latch onto our world."
:Vanus Galerion: "While the Dark Anchors have been able to pull portions of Nirn into Coldharbour, the Great Shackle has the power to steal our entire world."

Once at the main door, there will be a—brief—obstacle, the door is warded but Vanus Galerion can handle that easily.

:Vanus Galerion: "A barrier spell on the door? How pedestrian! Give me a moment and I'll open the way."
: 
:Vanus Galerion: "I must be weaker than I thought. That took a lot out of me. Once we get inside, you take the lead."

Vanus will slip inside the door and you can follow.
 

Exploring the Shackle
Once inside, Vanus will become your passive follower as you fight your way through the defending Daedra. On the way through you may find The Great Mooring, which hints at some potential weak spots in the system.
thumb|right|Somehow his impromptu experiment did not explode in his face
:Vanus Galerion: "I need to conserve my energy for dealing with the Shackle, so I leave the hacking and slashing up to you."
:Vanus Galerion: "We need to locate the source of energy that provides the power for the shackle."

Eventually, you will find the Power Chamber. Vanus will walk away to observe the nearby conduit.
:Vanus Galerion: "Remarkable! This could be what we were looking for."
:Vanus Galerion: "Very interesting. It appears to be similar to the cage I was imprisoned in at the Black Forge. Examine this pedestal and tell me what you make of it."

Once you touch the conduit, it will begin to spark in an alarming way before settling down.
:Vanus Galerion: "No! What have you done! Oh, wait. You reversed the energy flow. Good work! Now go upstairs and find the other conduits."

You will need to head up onto the catwalk to unlock the other magicka conduits, which are using a Storm Atronach for power. Before you leave, you can ask Vanus questions about the inner 
Before you head up onto the catwalk, you can ask Vanus questions about the shackle.

Gaining Allies
thumb|right|"Someone needs to pay for locking me away in this dung heap!"
As you move through to the passage to the north, you will hear someone call out for help. 
:Sage Tirora: "Is someone out there? I could use a little help in here!"

If you choose to, you can go into the side room and free the Soulshriven Sage Tirora. In return, she will

:"I thought I would rot in that cage forever." 
:I'm here with Vanus Galerion to destroy the Great Shackle.
:"What an excellent idea! You can count on my help. I'll go find Vanus and prepare myself for battle."

Continuing you will soon come across another prisoner.

:Treva: "You, there! Over here! Would you be so kind as to open this cage?"

Once he is free, he can also be recruited to help.

:"Someone needs to pay for locking me away in this dung heap!"
:Vanus Galerion and I are here to destroy the Great Shackle.
:"And I need to bust some heads, so I'm going to help you with your mission. I'll find Vanus and ready myself for battle."

Unlocking the Mooring
thumb|left|Use the Magicka Conduits
Once on the catwalk, you will need to unlock the three conduits found up there, which are guarded by several Daedra. Additionally, the book The Source of Power'' can also be found up on the catwalk, a notes several key details about the inner workings of the Great Shackle. Once you have unlocked all of the conduits, there will be a power backlash and the Storm Atronach powering the door lock will explode.

You can meet up with Vanus at the Mooring's door by either jumping straight down from the catwalk or taking the long way back. Once you arrive, you will find that you will have some unexpected company. Cadwell will be joining the last part of the mission, Sage Tirora and Treva will also be there if you freed them previously. You can time the time to talk with them before entering the Mooring.
 

Breaking the Shackle
thumb|right|Protecting Vanus Galerion while he casts the spells to weaken the Great Shackle.
When you enter, your goal will be right in front of you, the Great Shackle. Your companions will enter after you and Vanus Galerion will get in position immediately.

:Vanus Galerion: ''"Let's move out! The Great Shackle isn't going to destroy itself, you know?" 
:Cadwell: "Have at thee, vile Shackle! We're going to give you damned good thrashing!"
:Vanus Galerion: "Defend me while I cast this extremely powerful and fantastically impressive spell."
thumb|left|The Great Shackle is destroyed

While Vanus performs the spell, you and your team will need to fight off the waves of Daedra and Atronachs. At the beginning of every wave, Vanus will shout "encouragement" to you.

:Vanus Galerion: "Keep them off me! I have to concentrate and even the least distraction can be disastrous!"

There are six waves total: Three from the left portal, and three from the right. The portals will have a light indicating from where the next wave will come. The first fave features three Dremora, ranging from Beldakyns to Caitiffs. When the first wave is finished, Vanus will quip:

:Vanus Galerion: "Deal with those creatures! Must I do everything on this mission?"

This wave will have four Dremora spawn from the portals, including the healing Gandrakyns. Dispatch of them and Vanus will compliment himself:

:Vanus Galerion: "It must be electrifying to watch a master such as I as I work."

This is the final wave. The left portal will spawn two Frost Atronachs and Dremora Ferylkyn; the final wave on the right will spawn two Storm Atronachs and Dremora Morikyns. In both cases, the second Atronach appears when the fist reaches half-health. Plan accordingly.

When the final foe falls, Vanus will successfully finish casting this spell. And the results will be impressive, the magical lightning will arc through the Shackle and explosions of blue light, leaving only the metal framework. Vanus Galerion will be quite pleased with himself and declare the mission a success!
Galerion celebrates his victory|thumb|left
:Vanus Galerion: "I did it. The Great Shackle has been shattered! The threat of the Planemeld is no more!"

… Only for Cadwell to chime in with some pertinent information.

:Cadwell: "Jolly good! And, as soon as you deal with the planar vortex, everything will be right as rain!"
:Vanus Galerion: "What? Explain yourself, man! What planar vortex?"
:Cadwell: "The Shackle formed a planar vortex. Kind of like an Oblivion straw that will suck Nirn right through and into Coldharbour. Quite amazing how I knew that!"
:Vanus Galerion: "Enough! We can discuss this back in the Hollow City. I'll open a portal before this entire place collapses on top of us!"

Much like was hinted at in The Source of Power, the Planemeld has reached a critical point where it would continue regardless of the destruction of the Great Shackle. The Planar Vortex is still existent and all you can do for now is to regroup back at the Hollow City with Vanus in tow.

When you enter the portal you will find yourself outside the Mages Guildhall in the Hollow City. Speak with Vanus to complete the quest.
:"We have accomplished great things this day, my faithful friend!"
:Is the Great Shackle destroyed?
:"Was there ever any doubt? Between your skills and my formidable magical prowess, the destruction of the Shackle was a foregone conclusion. We aren't finished yet, however. Cadwell claims that we have more to do if we are to truly save Nirn."''

You will receive   and some gold. Incidentally, you have will have achieved one of the Groundskeeper's goals—recruiting the Great Mage. 
 

Notes
After completing this quest, the Mages Guild hall in the Hollow City will unlock, and Vanus and most of the other Guild members in Coldharbour will be found there.  Vanus will open a portal to take you directly to the hall if you wish.
 
Quest Stages