Praise the sun. Our Dark Souls Walkthrough provides tips for surviving the adventure, a guide to the entire world, and hints for slaying bosses.
Painted World of Ariamis
To enter this world, you should head to the huge painting in Anor Lando with the Peculiar Doll item in hand. You can find the Peculiar Doll by revisiting the cell where you started the game, during a second visit to the Northern Undead Asylum during which you face the Stray Demon. Once you have the doll and head for Anor Lando, you can backtrack to the lowest floor of the huge cathedral building.
The easiest way to get there is to warp to the bonfire in Anor Lando where the flame keeper is positioned. Head straight along the path, ride the lift down to the lower level, head forward again and then descend the stairs. Head left from there to enter the building, then work along the left wall as you battle a few assassins who can't be avoided. Then, when you're definitely ready to clear this optional area, you can investigate the painting on the wall.
When you check the painting with the Peculiar Doll in hand, it will suck you into the secret world behind it. This is an icy world, packed with snow and enemies. You appear on a suspension bridge spanning a chasm. There are wide holes that you cannot cross, in the direction from whence you came, so you're committed to clearing the area once you rest up at the first bonfire (which you should also kindle to its highest available level, just to make clearing the remaining stage easier).

Start up the stairs beyond the bonfire and ahead of you, there's a closed gate. Ahead of the gate, a weak enemy with a torch will rush you. Take him out, then look to the right where a couple more of the same enemy are probably on their way to ruin your party. Eliminate them and head in the direction from whence they came. You'll find the base of some stairs that you can climb up to the ledge over the locked door. There is another set of stairs just a few steps beyond that, which you can climb toward the upper right.
As you arrive at the top of those stairs, you'll be attacked by several more of the weak enemies. However, don't think you'll have it easy; there archers who will also fire on you from distant ledges. It's easy to take more damage here than you would probably like.

Once you've cleared the enemies in the immediate vicinity, you have a choice about how to proceed. There are wide stairs to your upper right, with an archer along them. Also, there's a narrower opening that you can squeeze through to the left. It's easy to miss but a more lucrative route. If you want, head up the stairs to the right and take out the archer, as well as the enemies that will rush you from further up the steps. Those two enemies are dangerous and capable of inflicting you with the Toxic status ailment, so make sure that you have blooming purple moss on hand just in case. You can check along the stairs for the Soul of a Proud Knight, but then it's a good idea to head back down the steps and left through the aforementioned tight space.
In that direction, you'll find a few more weak enemies as you climb the steps and toward the rooftop. Be careful as you arrive there, though, because some bird enemies will swoop down to attack. They're powerful, so make sure that you block and retaliate carefully, as you would with any dangerous foe. The corpse that served as the trap those birds sprung will give up the Soul of a Proud Knight.
With the rooftop clear, you should now head toward one edge of the building where the low wall falls away. Look down over that edge and you'll see a lower balcony with a corpse resting on it. Drop down and check the corpse to find the Dried Finger. Then head in the nearby opening to enter the building you've been climbing around for the last little bit.
Inside, you'll drop down to some planking where another weak enemy awaits, and possibly a bird if one of the two that attacked you on the roof fell off the side. Defeat any enemies you must, then look around the room. There are two sets of stairs here. One leads up and the other descends. Start with the stairs that descend to find the Soul of a Brave Warrior on a corpse. Be careful of the rats in the cellar, as they will try to poison you if given the chance to attack. You can grab the Painting Guardian Hood, Painting Guardian Robe, Painting Guardian Gloves and Painting Guardian Waistcloth from a chest they are guarding, in the corner of the room. When you have the loot, you can return to the stairs and climb them to arrive along the ledge that you would have reached if you ignored the detour through the narrow opening.

Ahead of the you, at the top of those stairs, there's a bridge that leads across a gap. On the far side of the bridge, an archer is on a ledge to the right of a doorway. You can cross the bridge and head through the doorway and into the nearby building, but be warned: it's full of enemies. There are quite a few of the guys who can inflict toxin on you (when they're not throwing firebombs) and there are some regular soldiers too. The archer may even enter the fray as you battle his fellows. Proceed carefully and watch for enemies to drop down from planking overhead.
When you clear the room, head back out through the opening on its lower side to find yourself on a wooden balcony. Ahead of you, there's a rope with a corpse hanging from it. Slash the rope with your melee weapon to drop the corpse and item to the ground below, where you can retrieve them later. Then reenter the building and head across it. Up a short flight of stairs, you'll find another opening that leads outside.
Now you're on a snowy ledge. Head left to claim the Large Soul of a Proud Knight from a corpse. Note that an enemy climbs up over the wall to attack here, but he's a weak one. After you have the loot, head back the way you came and this time follow the path that led right from the opening. You'll be able to cross a walkway that leads to one entrance to a circular tower.
Here, you have a lot of options about how to proceed. You can head down the stairs that lead left ahead of the tower entrance, or you can enter the tower itself and head climb it to find treasure and enemies.
If you start by going left, that will allow you to make strides toward creating a shortcut that leads back to the beginning of the stage, something you're likely keen to do. Start there, then. Descend the steps that lead left, then head right and through a building and descend along some steps to its lowest floor. Ahead, you'll see a mist-shrouded doorway.
Step through the mist and then start down the steps. Ahead, you'll see a group of armored phalanx soldiers with spears and large shields. They are in a circle formation, but you can start toward them and chuck a fire attack to get them to slowly advance. Keep your shield ready, as members of the group can throw spears to harm you if you're not blocking such attacks. Fire attacks can take out a soldier or two each time, if you're well-equipped, and you can retreat back into the building to give yourself time to safely gulp down liquid from your estus flask, if needed.
When you defeat the soldiers, check the edge of the courtyard to your right to find Humanity on a corpse that you dropped onto the area previously by cutting the rope. You can also check the far side of the courtyard, opposite the side from which you entered, to open the gate and create a valuable shortcut back to the bonfire. That saves a lot of backtracking.
Now you're ready to return to the area where you first approached the tower before descending through it to battle the phalanx soldiers. This time, you should start through the opening that had been directly ahead of you. Inside, a bird will attack, so be ready to block its attacks and counter in the confined space. Then you should climb the stairs that lead upward along the interior edges of the tower.
As you ascend, you'll find the area densely populated by the harpy birds such as the one you just defeated. There's not a lot of room on the stairs to fight, but typically if you have to fall you should try to fall left. There sometimes will be a nearby ledge to reduce the impact that a fall has. You can find the Soul of a Brave Warrior on one such ledge, even.
If you do manage to reach the top of the stairs, which requires defeating around three of the harpies or tricking them into falling so that you can proceed past them, you'll find a flock of birds gathered around an item. Snag that item to obtain the Red Sign Soapstone item. Then return to the courtyard area.
Along the side of the courtyard, to the right as you're looking out the doorway that you opened to create a shortcut back to the bonfire, there are some stairs that you can climb to a higher interior room. Do so, then exit left onto a ledge and start along it toward the right. You'll find a corpse. Around four weak enemies will attack you then, but they're weak and you can eliminate them just about any way you like. Then check the corpse to find the Soul of a Proud Knight. Nearby, another corpse is hanging from a rope and you can cut the rope to drop it to the snowy ground.
Return to the building and head around to find a ladder that leads to its lower floor. Descend the ladder, then head out an opening to the left. There, you'll find the Soul of a Brave Warrior and the Soul of a Proud Knight on corpses. There also is a lever on one pillar, which you can turn to provide a path to the bridge elsewhere in the stage.
Of course, such loot and a switch aren't going to be unguarded. Throughout the room, you'll face a number of the wheeling skeletons. They will see you, grab their shield and use it as a wheel to roll around the chamber, like skeletons you will have by now likely faced in the Catacombs. The easiest way to fight them is to block their charge as you stand near a wall. Then when the skeletons hit a wall, they will be stunned for a moment and you can take care of them.
Note that near the edge of this passage, left from where you turn the crank to open the way to the bridge, there's an illusory wall. Roll through it to reveal a series of passages beyond. These passages are populated by more of the wheeling skeletons and there are more fake walls.
From where you first pass through the first of those fake walls, proceed straight ahead until you come to an area where it seems you can only go left. To the right, though, there's a dirt wall you can roll through. Do so, then follow that passage forward and left to find a skeleton guarding a corpse. Defeat the skeleton, then check the corpse for the Annex Key.
Now backtrack to where you rolled through the dirt wall. Head along the path that led left from there and take the first right. You'll find another skeleton at the base of some stairs. Defeat him and climb the stairs. At the top of those stairs, you'll find a lone enemy. Defeat him (while watching out for his Toxic death breath) and then you can grab the Fire Surge pyromancy ability from his corpse.
Now you should put the annex key to use. Return to the open courtyard area overhead and work your way to the edge of the area where you'll see a number of wide openings with two or three steps leading down to a room that's not quite on the same level as the courtyard (but close). There, along one wall, you'll find a door that you can unlock with the key.
Unlock the door, then head up the stairs to reach a room overhead that looks out onto a snow-covered walkway. You can head out the door and reach an intersection. Go straight through the intersection and at the end of the pathway (which is guarded by more of the toxic enemies that toss firebombs), you'll find the Dark Ember resting on a tombstone.
Return to the intersection and this time break through the wood panel to the right to head along a hidden path where you can find Velka's Rapier on a corpse. Then return to the intersection yet again and follow what would have been a sharp left as you first approached it to find some stairs that lead up toward a higher level. There are some of the flame-tossing enemies along these stairs, so be sure to be careful as you ascend. At the top of the area, you'll also find several of the screeching harpies gathered around a hole in the ceiling. Be sure to not the harpies pounce you, particularly the ones on a higher ledge, as the pounce attack deals severe damage.
If you climb to the higher ledge where one bird will remain, it screeches and two more come to join it. Defeat them in a hurry and be sure to watch your life meter. Fire magic or aggressive melee warfare is critical here. When you win, you can check the corpse that the birds were guarding to obtain the Vow of Silence miracle.
Now head back down and continue to skirt the large hole in the ceiling. Descend along the steps that you find and head left to obtain the Mask of Velka, Black Cleric Robe, Black Manchette and Black Tights. Then return the way you came to the lower courtyard.
Along the back side of the tower, you may remember that there were stairs descending toward a long walkway with a dragon positioned along it. The dragon is awake, so you'll attract his unwelcome attention if you try to grab the items. He's guarding the Large Soul of a Proud Knight and a Bloodshield. The dragon itself tends to also drop the Dragon Scale.
To defeat the dragon, you'll have to proceed carefully. You can run up against him if you like and repeatedly hit him with a weapon, but he'll swipe at you from the side with his paw and even when that move is blocked, it does a lot of damage. The dragon also breathes toxic fumes, but those won't reach you when you're right up against his torso. You can either stay at a distance and pelt him with attacks at that range, or move in close and slash away at his gut as you gulp down estus flasks. Either strategy will eventually lead to victory, if properly executed. Further along the balcony, there's another of the dragons but you can't fight him.

There's another area that you might want to explore before you proceed along the path that will allow you to leave this region. Return to the courtyard and look for the stairs that descend along its right side as you enter the courtyard from the direction of the bonfire. If you descend those stairs, you'll find a number of corpses and enemies along the snowy ledges. You can search to the right to find the Acid Surge pyromancy (walk around behind a brick wall near the edge of the area to find it), while further down the ledges you'll find the Large Soul of a Proud Knight and two of the Soul of a Proud Knight item.
Defeat the enemies that you encounter in that area, then return to the upper courtyard and start through the lowest floor of the tower. On the far side, you'll notice the passageway that leads to a mist-shrouded doorway. That's the trail that you want to follow once you're ready to leave this area.
As you head along the walkway, you'll be attacked by a large number of skeletons. Some of them are in plain sight and will fire arrows at you or rush you as you approach, but note that there will be a few waiting behind pillars. They'll let you pass, then try to surprise you from behind.
Beyond the skeletons, there's also an enemy garbed in heavy black armor. He carries a Tower Shield that you'll receive from him if you defeat him, and he knows how to use it to protect himself. Hopefully by the time you face him, you've defeated any straggler skeletons and can fight him alone. Dodge his swing attack, then get around to his flank side and hit him with your melee weapon. He can take a lot of abuse, but you should have little difficulty as long as you block his attacks. When you defeat him, continue onward to the mist-shrouded door and step through it to reach the boss chamber.
Crossbreed Priscilla
When you enter this chamber, you'll see a translucent figure standing ahead of you, scythe in hand. This is Crossbreed Priscilla, but she won't attack you until you make the first move. Make sure that you have prepared yourself, then attack.
The first thing you should do when attacking is take off her tail, which allows for a weapon drop. You want that weapon. The second thing you should do is keep in mind that Priscilla is capable of turning invisible. She will do so once you have damaged her enough.
Even while invisible, Priscilla can be tracked by watching for her footprints in the snow, and for her spell effects. However, she primarily attacks with a lethal scythe that deals terrific damage. You need strong resistance against bleeding to survive this fight, since if your Bleeding meter fills that's an instant death. Havel's equipment provides the best protection, plus you can equip the Bloodbite Ring if you have it.
As you battle Priscilla, try to hit her once and if that happens keep wailing on her (as possible) to drain more of her life while you are certain of her position. If you don't know where she's at, you need to dodge around the area and keep watching for her spell effects so that you can find her and hurt her again. Running up the steps on the back side of the arena, then turning to face Priscilla so that she has to come to you (and so that you can pelt her with magic) is a great way to tip the scales in your favor.
Once you defeat Crossbreed Priscilla, you'll receive the Soul of Priscilla and an animation will follow that depicts you leaping from the high ledge that she was guarding. You'll appear back in Anor Lando and can resume your adventure.