The Elder Scrolls IV: Oblivion Guide - Main Quest Walkthrough
Breaking the Siege of Kvatch
Savlian Matius asks you to shut the Oblivion Gate that has opened up outside of the ruins of Kvatch. Savlian is willing to lead his men into the ruined city and attempt to reach the survivors that are holed up in the Chapel of Akatosh, provided the Oblivion Gate that is halting their progress is closed.
Closing an Oblivion Gate is a rather arduous task. You must first fight your way to the top of a tower inside of the realm, and then remove the Sigil Stone there. Since this is your first Oblivion Gate, be sure to stock up on supplies—such as repair hammers, health potions, magic potions, and arrows—before heading through. Things are going to be rough once you're through that portal, so it would be a good idea to save your game before stepping inside.
The nature of the enemies encountered once through the Oblivion Gate is dependent on your character's level.
Some minor Daedra will emerge as you approach the gate. Take them out and proceed through the gate. You'll spot some enemies up ahead once you're through the portal. You also may run into a guard named Ilend Vonius; he tells you that one of the survivors of the failed assault on the Oblivion Gate has been taken to one of the towers in this part of the realm. At this point, you can tell Ilend Vonius to leave Oblivion and assist Captain Matius outside, or you can ask him for assistance. It's best to just send him back to Kvatch, since it is almost certain that he will die fairly quickly.
A rather long and treacherous path awaits you. Start by heading down the northwest road from the portal. This path is very straightforward, but remain vigilant all the while. There are several enemies ahead, and some falling boulders to watch out for.
Be on the lookout for Harrada Roots as well. These are plants that will swipe at you as you walk by. As you move along the path, you should eventually be able to see three tall towers in the distance. Make your way over to them and start toward the middle tower. To locate the entrance, head east and keep an eye out for some steps leading up to a door. Head through the door marked 'The Blood Feast.'
The towers of Oblivion.
Be on guard as you enter, because there is at least one enemy on the lower level. Look around for a door marked 'Rending Halls' and head through. Upon entering this area, climb up the ramp and open the door. Most likely an enemy waits on the other side of this door, so be careful. A Blood Fountain lies off to the left; activate it to replenish lost health if need be. There are likely several enemies packed in this room, so remain vigilant. Once the area at the top of the ramp is clear, head through one of the doors here to reach the second level of The Blood Feast.
Follow the ramp up—keeping an eye out for enemies all the while—and open one of the doors that lead into the 'Corridors of Dark Salvation.' As always, remain vigilant, as there are likely several enemies waiting for you here. Head up the ramp and head through the door to the 'Planes of Oblivion.'
Once you're through this door, you'll find yourself on a bridge outside. This bridge is connected to one of the other towers. Walk to the end of this bridge enter 'Reapers Sprawl.' A man's calls for help can likely be heard upon entering this area. Ascend the ramp with caution, as a Dremora Sigil Keeper lies above, guarding the caged man. Take out the Sigil Keeper and loot the Sigil Keep Key from his corpse. Speak to Menien Goneld afterwards. Unfortunately there is nothing you can do to release the imprisoned man.
Head back down the ramp and exit through the door you entered from. Cross the bridge and return to the 'Corridors of Dark Salvation' area. Locate the locked Citadel Hall door at the top of this room. The Sigil Keep Key unlocks this door. Head up the ramp, but be very careful of the wall spike traps along the way. Exit this room through the door at the top of the ramp to reach the upper level of The Blood Feast.
Slay the Dremora Sigil Keeper to obtain the Sigil Keep Key.
Climb up either the ramp to your left or the ramp to your right and open the 'Ruined Portal to The Blood Feast' to reach an even higher level of the tower. Cross the bridge and follow the ramp up. At the top of the ramp is a door to the 'Sigilum Sanguis' area. It is an Easy quality lock, but can be opened effortlessly with the Sigil Keep Key. It would be a good idea to save your game at this point, as you will likely be attacked by several enemies at once upon entering the Sigil Keep. Take note of the Blood Fountain near the entrance in case things get hectic and you are forced to retreat.
Head up the spiral ramp to the second level of the keep. Kill any enemies on this level, and then proceed up the ramp here as well. The Sigil Stone should be right in front of you once you reach the top of this ramp. Approach the Sigil Stone and hit the A/X button to activate it while the prompt is on-screen.
The keep erupts into flames with a bright flash and you are instantly teleported out of Oblivion. Head back to the group and inform the captain of your success. When ready, tell Matius to proceed with the assault.
Activate the Sigil Stone to shut the Gate!
As with Oblivion, make sure you are prepared as things may get hectic once you step foot in Kvatch. Charge toward the gate and follow the guards into the ruined city. The southern plaza is crawling with enemies, but it must be cleared before you can rescue the survivors inside the chapel. Once all of the Daedra in the plaza have been dealt with, speak with Matius for further instructions.
It is now safe for the survivors to leave the safety of the chapel and join the remaining townspeople in the encampment south of Kvatch. Head toward the chapel, which is just north of the plaza, and proceed inside. Inside, you'll find the survivors still in one piece. Martin is in the main area of the chapel, likely near the shrine. Tell him of his relation to the Emperor and why he must travel to Weynon Priory. Afterwards, speak to Matius to complete the quest.
A new quest is added to your journal at this point, called 'The Battle for Castle Kvatch.' You don't need to complete this quest; at this point you can simply take Martin back to Weynon Priory to carry on with the main questline. This is, in a sense, a side quest. Refer to 'The Battle for Castle Kvatch' under the Side Quests section of this guide for instructions; otherwise continue on with 'Find the Heir.'