Dark Souls 3 Walkthrough: Cathedral of the Deep and Deacons of the Deep Boss Fight
Once you defeat the Crystal Sage in Road to Sacrifice, you will Lit the Bonfire and then Head Right towards the new Journey Cathedral of the Deep. We recommend to head to the Cathedral of the Deep bonfire first and then head back to the Firelink Shrine to upgrade your character. So let's begin with the Walkthrough.
Cathedral of the Deep
Done Upgrading your Character? Let's get down to the new chapter where you are going to deal with much higher difficulty enemies. Here the enemies will be having swords with fire along with the archers. You need to be extra careful with these little ugly looking foes. So once you start from the Cathedral of the Deep Bonfire head straight and you will be getting towards the Cleansing Chapel and lit the bonfire.
Now the real chapter begins where you will need to head outside the Chapel and then take the right path, from there defeat the praying Hollows. Head up and take another right and drop down to take the shortcut and walk towards another Chapel entrance where you will see the Ladder that will take you up and if you go straight then you will be fighting the Giant Crystal Lizard.
Once you get upstairs, you will be encountering some new types of enemies along with the Old Fat lady who is ever ready for hugs. SO head straight and then take the roof to get to the another side, kill all the enemies in your way. Then take the roof again to get down to the other side where four archers and one skeleton with a large Axe is waiting for you.
After dealing with them, head up until you find the giant door of the Cathedral. You will see a Giant waiting for you. Take right and head down where you find the Hallows throwing fire bombs at you, they are weak in health so two blows are enough for them. Keep coming forward, until you get another Big door which is actually the left Shortcut to Chapel.
Now head back to take up the Giant, but first, we need to get to the other side of the Cathedral so without taking any damage keep to the other side and get up and kill those archers and the Old Fat Lady. Then head down and you will encounter Cathedral Knight who is strong but slow. After dealing with him go straight Huge Spider who is so fast with his attack you must try taking him down before heading to his room. Killing him will give you Aldrich's Sapphire which can be used to recover FP from critical attacks.
Note: You can find the another Door to get in after finding the Red Sign Soapstone. This Door opens for a Bonfire and meet Rosaria - Mother of Rebirth.
Deacons of the Deep
Come back and now head inside the Left Area where the Giant is resting. First, you will be fighting the Dark Spirit Long finger Kirk. Destroy her and you will get Spiked Shield. Now Get down to the Entrance of the Cathedral and, this time, we need to the past by this Giant from the Ground section. Once you get there you will come inside the Church where two knights and Deacon Priests are waiting. Now head back side of the Church and you will enter the Boss Area.
Once you get inside you will see dozens on Hollow Priests are gathered and waiting for you. You must Start hitting the Enemy with Red Aura. The nearby enemies surrounding him will attack you so be careful. The Extras here have a lot of health compared to other Boss fights. Once you drain more than 30% of Deacons health head towards the Entrance where new Boss will spawn, but, this time, he has a good amount of health.
Finish him off quickly and soon you will be getting the Small Doll(Key) and Souls of the Deacons of the Deep. Now Lit the Bonfire and save your progress. Head back to Firelink Shrine to know more about your Progress and how to head to the next area. Thus Completing the Walkthrough and proceed to the Next part - Farron Keep. Make sure you visit our Dark Souls 3 Wiki page to know more about the game.