Archdragon Peak

To access this secret location, defeat the boss (Oceiros the Consumed King) in the Consumed King's Garden. After winning that battle, unlock the tomb in the back od his chamber and pick up the Path of the Dragon Emote from the body inside. Take this item to the plateau outside Irithyll Dungeon, and stand among the remains by the man-dragon hybrid's bones then use the emote.

Head on up as soon as you appear at this new location and grab some souls from the body off to the left. You'll soon run into a pair of enemies, defeat them them climb to the top of the big rock when you see it. Grab a Lightning Gem from the remains up here. After which you can return onto the path and come across three snake men. Defeat them then go back to the spot where you first got attacked and grab the Homeward Bones from the dangling remains, plus a Titanite Chunk behind the large rocks. Beyond this section is a bonfire and a body holding an Ember nearby. Going up the crumbling stairs, you'll find a Titanite Chunk on the left and some souls to the right. From here, you have two paths to choose from. Ignore the path below the archway and take the one to the left up the stairs instead. Kill the enemies and grab the Ancient Dragon Greatshield on the arch. There's a lever in this area to open the gate. Unlock it but keep heading left first to a small room with a Lightning Clutch Ring. Enter the gate afterward for a battle.

Boss Battle - Ancient Wyvern

This boss looks really intimidating but there's actually a way to one-hit kill this thing if you're strong enough. The key here is to target the wyvern's weakest spot. The head. Go through the side passages and find a way up to a point where you have a clear view of the head from above. Drop down from that spot and your character will perform a one-hit kill downward stab through the creature's skull.

You'll receive the Dragon Head Bone upon winning, after which you will be transported to the mausoleum. From your starting point on the balcony that boasts an impressive view, make use of the bonfire before moving on. Once inside, you will be greeted by a Drakeblood Knight. Now these things will keep coming unless you kill whatever is summoning them. So race upstairs to find the sorcerer at the opposite side. Kill the thing before heading back down to take care of the knight. Now for the rest of the loot in this place. Up the stairs you'll find some souls off to the left, while to the right is a gate with a Dragonslayer Spear behind it. Go through the door downstairs to the right of the open gate then past the door to the balcony on the left. In here is a corpse carrying a Titanite Scale and at the other end are a two enemies.

Look left here and there will be an elevator that connects to the one at the entrance of this area, while a balcony rests to the right and has some remains holding a Titanite Scale. Going left from here lets you spot a Stone Lizard down the stairs, collect the Titanite Scale from the corpse here too. Return to the wyvern's boss arena first to grab the freebies that were left there. Go drop off the wooden platforms to climb the other ladder to a pair of Twinkling Titanites. Next step onto the arch that you dropped down from and check below for some scaffold and return to the entrance of the area. Grab the soul by the bell at the plaza before going right to snag a couple of Embers and some Stalk Dung Pie. Follow the pillars around the corner to a body carrying a Ring of Protection. From here, walk past the bell and enter the very first structure you went into during the wyvern battle. There are souls to the right and up the short stairs to the left are Lightning Urns. A Titanite Chunk is sitting on the ledge over the crumbling dome, head down the ladder outside the window to get two Twinkling Titanites.

Returning to the roof, go through the door and up the stairs to face to average-size snake warriors followed by a large axe-wielding snake warrior at the top. Kill these things and check the balcony to find a good supply of Lightning Bolts and a couple of Titanite Chunks. That should conclude the loot hunting for now so go back to the mausoleum and take a right from the locked gate. This path here should be straightforward but dangerous all the same. Clear away all the enemies and once the big room at the end of the walkway is safe, look for a way out to a balcony and climb the ladder there to find a corpse with a Thunder Stoneplate Ring above. Follow the lower scaffold to a door where a Crystal Lizard can be killed for some Twinkling Titanites. There is also a treasure chest with Titanite Scales at the inner balcony too.

Moving on outside, defeat the two Stone Lizards and look to the left for some souls. There's a dragon above as well that will come down to attack. You can either kill the thing or run away from it. Managing to successfully defeat it rewards you with a set of differing Titanite types. If you choose to flee however, you will also have to avoid the Stone Lizards which will try to knock you down. Once inside the ruins, move along until you come to a room with an enemy in it. Here you have another snake sorcerer that constantly summons a melee monster. Go kill the sorcerer first then deal with his friend to get Ricard's Rapier. Moving forward, take the path straight ahead at the fork.

Be sure to leave the lever on the walkway alone for now and run up to the bonfire instead. Defeat the snake enemies in the courtyard at the bottom of the stairs, check the dais in the middle to get some souls, then climb the stairs across from you to a balcony housing a chest with some Twinkling Titanites.

Climb the ladder here and you'll find Havel who seems to have slain a dragon, and now has his sights set on you. Defeat him and you'll receive Havel’s Greatshield and the Dragon Tooth. The body next to the dead dragon carries a Titanite Slab. Back in the courtyard, go under the bell to find an Ember behind the gate. Ring the bell to create a path that connects to the boss chamber.

Boss Battle - Nameless King

This battle has two phases. The first part involves taking down the storm dragon, aptly named King of the storm. You will want to hit the creature's neck throughout the fight to deal damage effectively. He has two main attacks the first of which the dragon embeds a lightning spear into the ground then swoops down for a ramming blow. Simply move away from the spear the roll to avoid the swooping attack. Second is the fire breath which hits a wide area in front of the beast. You can actually move in from the side and attack the drake's neck during this. Kill the dragon and the Nameless King appears, initiating the second phase of this encounter.

This is where things get difficult. Consider putting on armor that grants full resistance to lightning as it will help tons. The Nameless King is primarily a warrior that does a variety of physical combos with his decent-ranged weapon. Dodge these attacks and counter as soon as you get an opening. Do buff your weapon with magic using Pale Pine Resin to deal extra damage. As you chip away at his health, he will start shooting lightning magic down at you. And while this does a lot of damage, you will get a good enough warning as the king prepares the attack. So be ready to dodge once you see him assume the particular stance.