Great Gate

The Great Gate has opened. You have kept Martin safe, so far so good. Enter the gate itself and view the giant siege engine before you that destroyed the walls of Kvatch.

You don't have much time in this quest. In fact, there's a time limit to close the Great Gate. The basic strategy of this map: Save at the start and keep it as a backup save for later on.

Immediately head towards the left and do a lot of jumping to avoid the pools of lava as you head for the first door to the Caverns Inside the caverns, slay any Daedra in your immediate way and head for the door to one of the lesser towers. Inside this tower, head for the top. Kill the Daedra guarding the Corpse Masher, then ride your way up, killing any other Daedra in the way. At the top, activate the Gate Control, then head back down through the door. Go past the opening gate, and deal with the Dremora. If you can't finish the fight quickly either ignore them or knock them off the ledge into the pits of lava.

Enter the tower. Immediate kill the Sigil Keeper. He has the Sigil key that you will need to enter the Sigil Stone sanctum. Proceed up into the Rending Halls, killing Daedra in your way. Be sure to use your map to avoid getting lost (there is a map marker). Exit back into the tower at the top of the halls, and continue to proceed your way up the tower.

Grab the Great Sigil stone at the top of the tower.

If you are short on time, then ignore the Daedra or knock them off the ledge (if possible). The only Daedra you really need to kill is the Sigil Keeper since he has the key. Be sure to have brought lots of Healing potions to this mission since there is going to be quite a bit of running. Also, enchanted weapons and armor help a lot.