The Yahar’gul Chapel is actually the same location as Hypogean Gaol, which you visited earlier, but under the Blood Moon you’ll have a new set of enemies and newly accessible areas.
Exit through the door to kill a Wandering Nightmare and then head up the small steps to the right and drop down onto a Rifleman for a Frenzied Coldblood (8) . The two Rabid Dogs below can be deadly, so try and drop down on them for some damage and then finish them off quickly without heading down the nearby stairs.
The Bell Ringer is actually just down the steps and to the left, allowing you to take her out without even drawing the attention of the nearby Huntsmen and Huntsman’s Minion. Continue down the next set of stairs, taking out the Huntsman on the left, and then grab the Blood Vial x8 before entering the chapel.
This area should be pretty familiar to you, with the exception of the new enemies that inhabit the area. There are three Hunters in the chapel, each with their own weapons and style of attacks, and together they are pretty deadly.
Start by sneaking up on the dual-clawed Hunter for a visceral attack that draws the attention of the other Hunters and then try to draw the Hunters apart by running away to lose sight of all except one. If you can manage to get each alone you should have no problem using your firearm to stagger and kill them.
Head down the chapel stairs to the bottom floor of the prison, where you’ll encounter an upgraded version of the Scourge Beast, and then head down to where you found Sister Adella to grab Blood Stone Chunk x2 off the dead Kidnapper.
Head up one floor to the cells leading to Darkbeast Paarl to kill another Scourge Beast and then check the back of the area for another Blood Stone Chunk x2 . You can now backtrack upstairs and exit the chapel to attack the Cramped Casket heading down the stairs.
Ignore the stairs heading down and take the stairs on the building next to the chapel, ignoring the dead end to the left with two Huntsmen, and kill the Rifleman straight ahead. You can now head up the stairs, suspended over the gap with a Cramped Casket, to kill the Bell Ringer before backtracking to the plaza.
Head under the stairs to kill another Cramped Basket, guarding more Blood Stone Chunk x2 , and then walk toward the Kidnapper’s corpse in the middle of the road to cause another Cramped Casket to fall out of the nearby carriage.
Pick up the Blood Stone Chunk x2 and then carefully walk toward the three Cramped Caskets in the middle of the road, which will automatically pull one over. The remaining two Cramped Caskets don’t like to split up and you’ll likely need to kill them together, just be careful or pull one with a Pebble.
Unless you have never been to this area before, which you should have if you have been following this guide, you can now backtrack to where you killed the Bell Ringer and enter the room to the left of the stairs, dealing with the Huntsman. The elevator returns to the area near the Yahar’gul, Unseen Village lamp, but what you want to do is enter the elevator and turn around to spot a gap halfway up.
This will lead to a new area with two Rabid Dogs and instead of heading into the building you should head down the stairs, killing the Wandering Nightmare, to reach a Scourge Beast facing away from you. You can now pick up the Blood Stone Chunk and enter the building upstairs, using the bath to port to a new area.
Head through the arch straight ahead to kill the Bell Ringer, along with her protector, and then return to the bath and exit the other doorway. Kill the Scourge Beast before grabbing the Blood Vial x6 and then enter the nearby doorway. Kill the Rifleman on the stairs and the Scourge Beast at the bottom before grabbing the Tempering Damp Blood Gem (5) in the alcove and then exit the doorway of bones.
This leads you outside to three Cramped Caskets, two of which are stationary and shoot spears at you from a distance.
Focus your attacks on the ranged Cramped Caskets first, as you kite the normal Casket around to avoid damage, and once the ranged ones are dead you can kill the melee Casket. Backtrack toward the bridge that hangs over the area and check near the mummy on the right side of the road for the Arcane Lake Rune.
Continue to the grand staircase, where another Cramped Casket awaits, and take the right stairs to a Frenzied Coldblood (8) . You can ignore the bridge and the rest of the street to the right, which leads back to the Yahar’gul Chapel area, and head back down the road.
Make sure to check the area to the right and left of the road leading to the boss to find Madman’s Knowledge x2 at each end.