Untended Graves

You can gain access to this location after defeating the boss Oceiros, the Consumed King. Upon doing so, look to the back of the bonfire and unlock the massive door. Grab the Path of the Dragon Emote from one of the bodies here then step up onto the dais. Look behind you for a fake wall that can be hit to reveal a path to the Untended Graves.

Go light the bonfire below you first before moving on where there is a Shriving Stone you can pick up along the way. Off to the left are some enemies including some Corvians and a Shaman. Quickly dispatch the latter then look into your casket to find an Ashen Estus Ring. Further ahead by the fountain is a soul and more bad guys. This time we have a pair of Grave Wardens and about five Bone Hounds. The dogs are guarding a couple of Titanite Chunks on either side of the path. Collect these first and move along on the side path where you'll spot a pair of Crystal Lizards that you can kill for some Titanite Scales. Onward to the next section where you'll probably expect to see something you know. Only to be met by darkness and a likely invasion from NPC Daughter of Crystal Kriemhild. The invasion chances increases if you are embered.

Once again, if you're expecting to find a bonfire at the top of the path, you'll quickly realize that there isn't one. What you do have however is more darkness and a horde of monsters. Kill all of them and move forward into the area where you faced a different version of Gundyr previously, and you will be welcomed into a boss encounter.

Boss Battle - Champion Gundyr

Here we have an alternate version of Iudex Gundyr who excels solely on physical attacks. For one, his weapon has a fairly long reach so be careful when you move in to do damage. Attack from behind if you can then strafe around him as you wait for an opening. You might also want to try using some Gold Pine Resin on your weapon, or equip something that is lightning-based. This allows you to deal more damage on Gundyr whenever he's on the water. If you need to heal, move far away from the boss before chugging down those Estus Flasks to be safe.

Beyond Gundyr's chamber is the path that you expect to lead to the Firelink Shrine, which it does but the place is quite a bit different from what you would hope to see. For starters, Black Knights have taken the place of the regular Hollows. There will be a couple of Black Knights waiting on the path just past the boss chamber. Kill these one at a time and then go right when you can further along the path. You will find a Bone Hound along with another Black Knight who happens to be blocking access to a Homet Ring. On the path to the west of the entrance, you should notice that the Hollows from back at the beginning of the game are gone. And in their place is a Black Knight and some remains that you can score a Chaos Blade from.

Enter the shrine and you'll find it very much empty. Grab the Coiled Sword Fragment from the unlit bonfire and explore the rest of the area. You will find items instead of people in some sections, such as the Blacksmith Hammer from where Andre should be, some Hollow Ashes in Yoel of Londor's corner and if you try to follow that path that leads to Irina in the real shrine, you will instead be met with a wall that you can hit to get the Eyes of a Fire Keeper. The Handmaid will still be present however and you can purchase items from her. Although keep in mind that if you choose to be mean and kill the Handmaid, she won't come back to life. So best keep that murderous streak to yourself.