Dark Souls 3 Walkthrough: Catacombs of Carthus, High Lord Wolnir Boss Fight
Once you defeat the Abyss Watchers in Farron Keep, you will Lit the Bonfire and then Head Right towards the new Journey Catacombs of Carthus. Here you will have to face some new kind of Enemies which includes Catacombs Skeleton, Skeleton Wheel, Grave Warden Skeleton and much more. So let's start with the walkthrough.
Catacombs of Carthus
From the Abyss Watchers Bonfire, Head down to the Catacombs of Carthus area and then take first Left. You will be encountering few Catacombs Skeleton, now these are different skeletons as they keep on getting back up then face Grave Warden Skeleton on the bridge. Remember that the enemies with Red Eyes are more Powerful and difficult enemies so far. Now keep walking on the bridge and on you left you will find a Pillar to jump on and enter the enter the cave to collect the Pyromancy Tomb.
Now take Left and Enter through the Illusory Wall, walk straight and then take left as we are going first heading to the Bonfire to save our Progress. Climb the ladder there is a trap behind and a Skeleton with an arrow in the front. Keep following the path and head down and finish off the Skeleton army down there. Keep heading down towards the Hallway until you find Anri on your left and she will ask you to find Horace.
We will be doing it later but first the Bonfire, so head out and down to the bridge and be careful of the Skeleton Wheel Trap on the Bridge. You must stand on the edge to avoid getting contact with the Wheel. Here there are Pots which carry dark affinity king of souls which follow you and hit you. Try to avoid hitting the Pots which have the lids on them carry these souls and the Pots with the Bones are good pots which don't carry anything.
Catacombs of Carthus Bonfire
Head straight and fight the Warden Skeleton then take the right to deal two of more Warden Skeletons. Take Right and the again Right, but be careful of the Skeleton Wheel Trap here as then take First left to Lit the Bonfire and save your Progress or upgrade your character. Once you're done upgrading head left and try to follow the Skeleton Wheel to get past the trap quickly.
Here you will encounter the Hound-Rat and Large Hound-Rat, kill then and head Right. If you see on the ceiling there are these Writhing Rotten Flesh which falls as you passed the area and there are Skeletons with Wheels which can burn your stamina fairly faster. Take left and collect the Carthus Bloodring and then head back to the first path and take on the skeletons and then take a left U-turn to head towards the Boss Fight.
Head down the Path, take a right and towards the Last Tunnel where you find the Crystal Lizard down the right side. Now here walk slow and easy to take on the Warden Skeleton off the Edge. As per the message you shouldn't be using the Suspended Bridge as it is wearing thin. Take the Alternative path on the right and walk up where you will find Anri and then Drop down to get past the Bridge. There is Two path now once the Bridge falls and take the optional area or take the Boss first.
High Lord Wolnir Boss Fight
Open the Door and Start the Boss fight by touching the Goblet and this isn't a particular Hard fight so don't take it too hard. Simply follow our Lord Wolnir Boss Fight Guide here to take him down easily. Once you have defeated him Lit the Bonfire and save your progress and Upgrades. Thus Completing the Walkthrough for the Catacombs of Carthus and Start with the next part to Fight the Old Demon King and the Optional Area - Smouldering Lake. Don't Forget to Visit your Dark Souls 3 Wiki Page to know more about the game.