- After the first Boulder o' Bones has rushed down the staircase, run inside of the passage in front of you and kill the Skeleton wearing the pointy hat. The next time the boulder hits the metal bars, it will explode and drop the shard.
- Found in front of High Lord Wolnir during his boss fight. Pick it up easily during the fight; however if you do not pick it up during the boss battle, it can be found afterwards on a corpse in the back left of the boss room with the goblet.
- From the Abyss Watchers bonfire, head into the catacombs and to the first bridge. Roll onto the platform below it and head straight forward to pick up the tome from a corpse against the wall.
When you first enter the Catacombs of Carthus, a few steps past the entrance, you'll see a long staircase down below. From this spot, heading left will let you explore the area, while to the right is a shortcut that takes you down to the base of the staircase. There is some good loot and plenty of fun enemies to kill when you go left, and across the walkway. The skeletons with glowing white eyes will respawn, and need to be killed twice. This area is fairly interconnected, but it is worth exploring for loot and souls.
The area just before the staircase is not very big or complicated. While exploring you will encounter a good number of skeleton enemies. The most dangerous of them are the Carthus swordsmen, especially the one dual-wielding shotels. A blunt weapon will be very useful against them. If you have decent Faith, a blessed blunt weapon is the ideal instrument for this area (and the area beyond). Points of interest:
-> When you first cross the bridge at the beginning of the area, look down to the left and you will see a platform you can drop down on. A bow skeleton will rise up and greet you. Go through the opening there, and just a few steps ahead is the Carthus Pyromancy Tome. Watch out, as there will be a falchion skeleton ambushing you. A few steps behind this skeleton is an illusory wall that opens into the room where the shotel swordsman is.
-> From the room where you find the two swordsmen wielding Carthus Curved Greatsword, exit through the far end of that room, a group of 4 skeletons will want to say hello to you. Deal with them and take the stairs down. Now if you follow Anri's story up to this point, he/she should be just ahead. Past him/her is a platform where you will find a Crystal Lizard who drops a Twinkling Titanite. Once you are done here, head back to the staircase.
There is not much in terms of treasure in this area, aside from the Carthus Tome. If you are on NG, you probably want to collect the 2 Titanite Shards in the room where you find the greatsword swordsmen.
Be careful going down the staircase, because a Boulder o' Bones will roll down on you, Indiana Jones style, and knock you off or kill you.
If you don't feel like exploring… At the very beginning of the area, go right, and there are some platforms you can drop down to get you to the bottom of the downward walkway. Once you land at the bottom and take a few steps, the Boulder will trigger and roll down towards you.
At the base of the staircase, go through the opening there, and to your immediate right is a skeleton with a pointy hat. Killing him will make the Boulder explode the next time it hits a wall. The first time this Boulder breaks, it leaves behind an Undead Bone Shard.
Move on from this point, you will run into more skeletons. Some of them will revive once. Once you get to the middle section of the hallway, you will see a large number of breakable pots. By the wall behind all these pots is the Carthus Milkring. The pots that contain no bones will release dark missiles homing on you when they break. They are easy to avoid, but if you break them when you are close to them, chances are they will chain-break and you will be hit by a lot of missiles at once.
Go past the pots and you will find another greatsword swordsman, and more skeletons. At the end of this path, you can drop down to the left to get to the floor below, or turn right and face two curved sword swordsmen. There is a pressure plate in that corridor which will trigger an arrow trap. Next to the plate is a consumable soul. Behind the swordsmen is a hole that opens down to the floor below, and behind it is an Ember. Take the path to the right of the hole, grab the Large Titanite Shard to your immediate left, then go right. After a few steps, a second Boulder o' Bones will fall down behind you. Take the left turn just ahead of you, and you will find the Catacombs of Carthus bonfire.
From this bonfire, as you move toward the walkway, this will always trigger the Boulder o' Bones to the right. The path forward is to the left. Head downstairs while avoiding the Boulder. Now you can follow the right path or the left path. Straight ahead is a shortcut that needs to be opened first.
Go to the right and you will find several Hound-Rats and a Large Hound Rat. Turn right again. There is a fair number of Writhing Rotten Flesh on the ceiling, so be careful. There are 2 Titanite Shards on the way. At the end of that path are several Skeleton Wheels, and the Carthus Bloodring in the corner - watch out, there are a few Writhing Rotten Flesh right above the Bloodring too. Once you are done here, go back to where you find the rats earlier.
From there, you can see a shotel swordsman in the distance. Make your way toward him. There are 2 Titanite Shards by a column. There is an opening with some stairs that lead up the second floor, but going up this way is a bit more dangerous. Instead, wait until you reach the shotel swordsman. Once you have taken him out, look to the wall between the last two columns, there is an illusory wall there, on the same side as the opening behind the swordsman. Past this illusory wall is a staircase that also leads to the second floor. Up here, you will find another shotel swordsman - this one can revive once. By the wall is the Grave Warden's Ashes. Keep exploring this floor, you will find a Large Titanite Shard, then another shotel swordsman (great!), a swordsman with bow (or bowman, since he does not seem to have any sword equipped), and a second pointy-hat skeleton. There are 3 Carthus Rouge near the bowman.
Now head back downstairs, to where you find the first shotel swordsman, and move on. In the cave tunnel ahead, there is a Crystal Lizard that will drop a Fire Gem. Past it is a greatsword swordsman. Go to the right as you exit the tunnel. A few steps ahead, you will see a lot of bones lying around. Two skeletons will assemble themselves; the rest will wake up when you get to the wooden bridge. By the wall near the bones is a lever that lifts the portcullis, opening a shortcut to the previous section. Pick up the Ember there before you leave.
From here, head toward the bridge. You can take the bridge, or take the sloped path to the right of the bridge. If you take this path, at the end you will find Anri, provided you have exhausted his/her dialogue in your previous encounter. You can drop down from here to get to the other side of the bridge. Beyond the bridge is the room where you will face High Lord Wolnir.
The bridge can be collapsed by hitting it. Once the bridge has collapsed, it becomes a ladder that allows you to climb down and proceed to the transition area between the Catacombs and Smouldering Lake. In this area, you will find a demon, a mimic, and a large number of reviving skeletons. You can get rid of the demon easily by let it fight the mimic and the skeletons. The mimic here drops the Black Blade upon death, while the demon drops the Soul of a Demon. There is a Large Titanite Shard by the stairs behind the demon. A safe move here is to simply run past the demon and the skeleton army, exit the hall, then turn right to get to the bonfire. The Witch's Ring is by the wall ahead of you as you exit the hall. A short walk past the bonfire is Smouldering Lake.
- Some of the enemies may reanimate once after being killed; make sure you see your soul count going up after dealing a killing blow, otherwise be ready
- To reach Smouldering Lake, you need to break the wooden bridge outside of High Lord Wolnir's throne room and then climb down to a platform below
- If you look down from the spot where Anri of Astora stands near the brige, you can see the cave with Horace the Hushed in Smouldering Lake