Head down the stairs and hit the switch to the left by the closed door. Inside is one Soul of a Great Hero and three Dragon Charms. Collect the items, then go through the hallway on the opposite side (do not head down the stairs to the right of the room with the items). If you have a ranged attack, inflict as much damage as you can to the enemy in the room just ahead. If you can't kill him or don't have a ranged attack, head down the stairs to the left, then enter the room to the right where the enemy was standing.
There are two enemies in the room, as well as two bodies on altars. Attack the bodies on the altars, then engage the enemies. If you attacked the first enemy with a ranged weapon, you can fight him outside of the room by himself. If not, spread the two enemies out so you can battle them individually. They have a longer attack range than most other melee enemies, so be careful as you approach. Take out both enemies, then open the five chests in the room to obtain a Titanite Slab, five Old Growth Balms, one Soul Vessel, a Catarina Helm and 50 Destructive Greatarrows.
Leave the room and continue down the next hallway. One enemy attacks almost immediately from the left, while another begins to make his way toward you from the right. They have long reach and poison-based weaponry, so use the length of the hallway and even the coffer room you just left to make sure you've not fighting in a confined space.
Defeat the two enemies, then head back to the hall where they originally attacked. Be careful of the pressure stone in the middle of the hallway (near the point where you initially enter). If you step on it, a dart shoots from the left. Two more enemies await at the far end of the hall. Both of them are "sleeping" as you approach, so inflict as much damage as you can before they attack.
Watch out for the sorceress in the room to the right. If you move too far down the hall, she will attack you with spells. Battle the two enemies near the point where you entered to avoid having to deal with attacks from the sorceress as well. The coffer at the very end is rigged to launch a series of arrows at you when it's opened, so make sure you have your shield at the ready immediately after opening it. A Bonfire Ascetic is found inside.
Make sure you open the coffer before you move into the room to the left, because it will take some effort to get back to the coffers once you move into the adjacent room. With the two enemies down, use ranged attacks on the sorceress and the other enemy in the room to the left. If you do not have ranged attacks, move into the room to engage them at close range. Take out the sorceress first, then handle the melee enemy.
Pick up the Human Effigy on the far wall, then use ranged attacks to kill the enemy that's visible through the hole in the door ahead. Once that enemy is down (or if you don't have ranged attacks), step on the pressure stone in front of the door to rotate it. Do this several times until the large opening is at the bottom, then take down the enemy or simply head through the doorway if the enemy has already been dispatched.
Make your way down the hallway to the right, then down the stairs ahead. At the junction in the middle, head left to find a Repair Powder and right to find a locked passage. Pick up the item, then continue straight to find a hole in the ground. Jump over the gap in the floor and continue down the hall until you reach a closed doorway. Use a ranged attack to hit the switch to the left, then head into the opening on the left. Before you enter, head down to the end of the hall and use a ranged attack on the switch above.
Go back to the newly opened doorway and engage the melee enemy that attacks, then use ranged attacks on the enemies to the right in the room down the stairs. Be careful of the pressure switch at the top of the stairs. It triggers a spike trap along the staircase.
With the enemies taken care of, make your way down the stairs to find the Soul of a Hero and a Human Effigy along the staircase, as well as three chests in the room at the bottom that contain three Boltstones, three Bleed Stones, three Twinkling Titanite, three Petrified Dragon Bones and a Puzzling Stone Sword. If you did not hit the switch at the end of the previous hallway, the chest with the Puzzling Stone Sword will not be accessible.
Head back out to the hole you previously jumped over and fall down into it this time. Turn around and walk away from the sharp corner (an enemy awaits around that corner that you don't need to engage yet). If you wish to go toward the sharp corner where the enemy awaits, skip ahead to 2A. If not, go down the stairs and be wary of the spikes ahead. Use ranged attacks from the stairs (or just below the stairs) to take down the enemy sitting in the spikes ahead. If you can get his attention, he'll move into the spikes and kill himself.
There are several items within the spikes. The item near the first enemy gives you three torches, while the items on the far side of the room (to the right) are three Twinkling Titanite, five Holy Water Urns, a Human Effigy and chest at the far end of the room that holds a Dragon Stone. You can gain access to the chest by hitting the switch on one of the pillars between the rooms (along the narrow pathway between the spikes). If you go for the items on the far right, another enemy drops down to attack.
If you take the narrow path between the two sets of spikes, there's a dilapidated staircase at the end that eventually leads to the boss battle. For now, use the narrow path to reach a ladder on the right side, near the end. Climb up the ladder to engage a sorceress enemy to the left.
Once the sorceress is down, you can continue forward to fight another sorceress and a second enemy in the next room, or turn around to find a bonfire. If you wish to get to the bonfire, turn around and head toward the end of the path. Jump over the gap to the left and into the next narrow corridor. Light the bonfire to the right, then continue to the right to find a Sanctum Crossbow.
Head back the way you came and take down the sorceress in the room ahead, but the other enemy is in spirit form. To the right of the entrance to the room is another bridge. Make your way across the other bridge and down the broken stairs to the left to find another coffer that contains a Bloodbite Ring +1. Head back up the stairs and then down the next set of stairs to the left to find a room ahead with three more spirit enemies that use multiple ranged attacks. Attack the statues that line the room to materialize all of the spirit enemies, then take them down.
The room holds an Eternal Sanctum Key and a Sanctum Knight Helm, so you need to head down there. Once you've collected the items, you can drop back down into the area with the spikes and then head up the stairs to engage the enemy you skipped earlier (the 2A path).
Take out the insect enemy around the corner, then use a ranged attack to dispatch as many insects below as you can. Once you've taken down as many as you can see, drop down into the room below and kill any remaining insects. There are three on the ceiling, so even if you kill all of the insects you can see, you'll have to deal with at least three upon dropping.
Deal with the enemies, then pick up the five Lifegems, one Old Growth Balm, and 10 Dung Pies on the ground in the room. Head up the stairs to find 20 Poison Throwing Knives. Just beyond the item, one last insect awaits on the ceiling. Take it down, then continue up the stairs, then up the ladder at the top to climb into the room above.
Open the chest in the room to obtain Flynn's Ring (increases physical attack when you lower your equipment load). Head through the doorway and drop down into the hallway below to find yourself near the area with the spikes and two sorceress enemies.
Head back across the bridge where the sorceress were (above the spikes), then go down the stairs and make quick work of the enemy at the bottom. Turn around and use a ranged attack to hit the switch to the right of the stairs. It's dark, so the switch can be hard to see. Adjust your brightness settings if necessary. Continue to the right, down the next flight of stairs and into the narrow corridor to the right. Move through the opening near the end of the corridor, to the right, then make your way down the stairs.
Pick up the Old Growth Balm in the room and continue through the opening and down the next flight of stairs. Head down yet another flight of stairs to engage an invader, Jester Thomas. Stay close to the invader, but watch out for his fire attacks. They have good range and execute quickly, but if you strafe around him they aren't difficult to avoid. Defeat the enemy, then walk through the mist to the right and down... you guessed it, another flight of stairs.
In the water-filled room ahead, there are five large monsters with a bonfire at the very end. While the bonfire is optional, you need to head all the way to the left side of the room. Two of the monsters are visible from the entrance, the remaining three are off to the left. You can take them down with ease if you have ranged attack options. If not, you'll need to close in on them and take out their feet while avoiding their biting and stomping attacks. They will also jump in the air to perform another stomp-like attack that will drain your stamina completely if you try to defend against it. When this happens, get away from them quickly.
Take out the enemies or simply run past them to avoid combat. When you make it to the far left side, head up the stairs and interact with the object at the top. It requires the Dragon Stone, which you picked up in the chest located in the room with the spiked floor.
Head back down the stairs and to the left to enter the doorway ahead. Continue into the next room and through the cave to find a Drakeblood Greatsword at the end of the path. Turn around and head back into the room, then attack the glowing pillar to activate the lift to the left. Step on the stone in the middle of the lift to ride it up.
When you reach the next floor, you can head to the left and take another lift to the top (which leads to the first bonfire you encountered in the area). Unless you need to go back to that bonfire, go straight ahead through the doorway. Make your way across the bridge and up the stairs. In the next room, head through the opening to the right and drop down. Continue dropping until you reach the bottom, then go through the doorway. Drop down to the ledge below and to the right, then head left and drop down to the next platform below.
Go up the and through the doorway on the right to engage a rather agile enemy. If you're not agile yourself, you'll need to avoid his attacks and hit him while his shield is down. Be careful, as he will attempt to knock your shield away if you're using one. He fights very similar to a human foe. Lances and spears work well against this enemy because you can attack from behind your shield and keep your distance.
Take out the enemy, then head out the way you came in and continue to the right. Drop down to the platforms below to the left, then proceed down the small set of stairs. In the corner of the hallway ahead are 10 Hexing Urns. Pick up the items, then continue around the corner to engage another agile enemy. Defeat the enemy, then jump down where the stairs have crumbled (in the corner just beyond where the item was). Turn immediately to find another set of stairs and continue down.
Head to the right, then around the corner to the left to find another agile enemy patrolling the halls. Take him down, then proceed around the next corner. In the middle of the wall to the left is a hidden doorway that leads to a bonfire. Interact with the wall near the middle to open the hidden doorway. Light the bonfire, then continue around the next corner and down the stairs ahead. One more agile enemy awaits below, but if you did not see a patrolling enemy, there's a good chance there are two agile enemies in the room. Make quick work of them, then head to the far side of the room.
Go left down the next hallway to find a room at the end (on the left) with a set of Drakeblood armor. Collect the loot, then exit the room and head to the far right. Jump over to the ledge left of your current position. If you land on the upper ledge, drop down to the ledge just below.
Move toward the stairs in the corner and drop down to the next platform below. You can also jump over to the adjacent ledge as you make your way down. There are two more agile enemies here, but the small area holds three Vine Balms, six Twinkling Titanite, the Large Soul of a Brave Warrior and five Smooth and Silky Stones. Collect the items if you wish, then continue to use the crumbling stairs to drop down until you reach the bottom level and enter Dragon's Rest. Head through the midst to begin a boss battle against Elana, the Squalid Queen.