Nightmare of Mensis is a location in Bloodborne. You arrive here from the Lecture Building 2nd Floor exit.
The Brain of Mensis produces a passive effect, causing the player to generate Frenzy. This effect is disabled by breaking line of sight with the lit window. The player's Frenzy will continue to build for a few seconds after breaking line of sight with the lit window.
- Large Nightmare Apostle (drops 3403 Blood Echoes)
- Choir Intelligencer Edgar (Ludwig's Holy Blade and Augur of Ebrietas)
- Eye Rune - From the first lamp, take the rightmost path. The Eye Rune is guarded by two giants.
- Shaman Bone Blade (x3) - At the end of the room with the Giant Spider, before the catwalk where the Hunter is fought.
- Moon rune - The bottom of the spiral staircase connected to the boss area, past a large group of enemies.
- Iron Door Key - Found in the second half of the boss fight with Micolash, Host of the Nightmare.
- Moon rune - Bottom of the giant pit in the hall with the dwarves. Take the single elevator cage down into the abyss and perform the "Make Contact" gesture at the Brain of Mensis. You will receive the strongest Moon rune after 30 seconds.
- Blood Rock - There are two paths to this item. The first path requires the Iron Gate Key. The door is near your first encounter with the puppet enemies and the start of the Micolash boss fight. This door brings you to a bridge covered in Insight Items. On one side of the bridge, there is a structure with another area you can jump down to. This item is on a dead body in said area. The second path is reached by crossing the bridge with 3 Brain Trusts and passing the room with spiders, you'll find a hole in the floor. Enter this hole and look for a door that leads to the bridge with the Insight Items.
- Choir Bell - Easiest way to this item is after Micolash fight. Obtain the iron door key during Phase 2 of Micolash and then go back to the bottom floor library (Micolash fight Phase 1) and look for a broken shelf that leads to a hallway with a gate locked at the end. Use the iron door key and proceed across the bridge picking up all the items. Found in the room at the end of the bridge. There are two spiders and one Brain Trust across some thin metal rafters. In the chest behind the brain enemy. Bring frenzy resist clothing and plenty of sedatives.
- Tempering Damp Blood Gem (x5) This gem is a DROPLET, meaning that it can fit into any socket, including tougher to find shapes such as Triangle and Waning. It gives a whopping +18% Physical Damage bonus. It is found on the way to dropping the Brain of Mensis, on the second half of the bridge with the three Brain Trust enemies.
- Silver Beast
- Parasite Larva - spawned by Loran Silverbeasts upon death
- Giant Lost Child
- Chime Maiden
- Mergo's Attendants (All Varieties)
- Mergo's Chief Attendant
- Skeletal Puppets
- Nightmare Apostles (spiders)
- Rabid Dog (Crowhead variety)
- Carrion Crow (Doghead variety)
- Maneater Boar
- Winter Lantern
Path to Micolash, Host of the Nightmare
Progressing forward from the entrance of the area, you'll encounter a Loran Silverbeast crouched behind a wall. These are strong but not too tough, and are very vulnerable to fire, but they do have an bolt retaliation that hits a wide area if you stay close for too long. They also spew out two Parasite Larva upon their death, though this can be countered by killing them with fire or a visceral attack.
The first lamp is located past a couple of Silverbeasts up the hill, tucked behind a ruined wall. At the top of the rise the area opens up and splits into two side paths; ahead of you is a large castle. Take note of the windows on the left - if you remain in the open a light will shine from within the castle causing you to build up Frenzy and dealing damage. You can hide behind taller walls to avoid this, and you can use it to your advantage, as enemies caught in the open when you are hidden will take damage from the light as well.
Take the path to the right first; it leads past some stone-throwing Giant Lost Children and to a device that does not function yet - you can lure the Giant Lost Children down the path a little way to let the frenzy kill them if you're having trouble, but their attacks are slow and well-telegraphed. At the end of the path is the Mergo's Loft: Base lamp and a lift leading up, which is unavailable until later.
Going left from the main lamp, you will run into three separate Silverbeasts, one standing in the open, one at the start of the bridge leading to the next area, and one patrolling at the end of the bridge. They can be dealt with easily by luring them out where the orange light will start to hit them, then running back to the lamp where you can take out what remains of their health from the relatively safe area behind the wall. Once you defeat them and cross the bridge, you will reach a path leading to the entrance to the castle, which is mercifully out of sight of the frenzy-inducing orange light. Alternatively you can use a Blue Elixir to make yourself harder to see and sprint past the whole area. This keeps you well out of the way of the frenzy build up and the Silverbeasts won't react to you until you're literally running past them, so you can get out of the way quickly.
Along the path there will be a total of four Giant Lost Children lying in wait. Two are hidden in the rocks on the left, while two more stand near the castle's entrance door (though one remains sleeping until you approach). The first can be safely dealt with, but the remaining three are somewhat trickier, as the one on the right that is awake will fling rocks at you as soon as you enter his line of sight. If you try to deal with the one on the left first, you will do so under constant barrage from behind, and it's very easy to get stuck in the rocks while trying to fight and avoid the flying boulders. A slightly easier method is to simply run to the right first, where you can draw the two Yetis back behind a large rock hill and deal with them without being attacked by the third, but this requires you to fight two at once. Whichever way you deal with the threats, head to the door and take a left before entering, where you can find a Blood Stone Chunk just out of sight by the castle wall.
Moving into the castle, you will spot a room full of Nightmare Apostles (spiders). Before dealing with that room, take an immediate right onto a short staircase, then head into the opening on the right which leads to a small balcony, and more importantly, the Bell Ringer for the area. Kill her to prevent her from spawning invaders, then press onward. Exit the balcony and take a right again, where you will spot a lone Nightmare Apostle hanging from the ceiling. Knock it down with a pebble and kill it, then walk slowly along the small bridge to the left. Two more Nightmare Apostles will drop from above, so back up and fight them in the safe corridor.
Now, to deal with the Nightmare Apostles. Once the ones in the main room start falling, they all drop in to fight, and as they attack quickly for high damage, they can easily overwhelm you before you can even get a chance to fight. Complicating things even further is the Large Nightmare Apostle in the center of the room, whose attacks have a tremendous range. Fortunately, however, it can't get through either of the two doors leading out of the room, and if you head back the way you came, the normal Apostles might get stuck trying to follow you as well. Once the small ones are dead, carefully deal with the bigger Apostle and continue to the far end of the room, where you will find 6 Shaman Bone Blades on a body.
Head right out of the room and across a bridge, but be careful - there's a hunter (Choir Intelligencer Edgar) waiting to fight. He uses a thrusting sword and a Rosmarinus, but he has relatively low health and should go down easy. He is easily parried so bait his attacks and do massive damage. In the next room, head to the left before going down to find a chest containing 2 Yellow Backbones. You'll see curious little armoured enemies wandering around in here. These are Mergo's Attendants which unlike almost every enemy you've faced in this game, are largely ambivalent towards you. If you get close enough they'll aggro but largely they'll just wander on their own paths. Don't take this to mean that they're easy though, they normally come in small groups of two or three and it is quite easy to get staggered by them.
Once you've fought the Attendants, look to the right side of the room, where you should spot a green light at the far end of a corridor. Go down that way and activate the lift shortcut leading to the Mergo's Loft: Base lamp. Use it if you'd like to change your spawn point and/or spend some of those blood echoes, then breathe a well-earned sigh of relief and head back up.
Fight the Attendants again if you need to, then go through the wide opening on the right. Take an immediate right to grab a Beast Blood Pellet behind a screen, then go back the other way. There are several more Attendants blocking your path. Deal with them and continue on to a big flight of stairs, but don't go down just yet - 2 Blue Elixirs wait at the end of a long, curved path to the left of them. At the bottom of the steps, you'll find a Mergo's Chief Attendant wielding a chain and axe, and what's more, her attacks deal rapid poison damage. Her move set is quite similar to that of the Executioner (or the Butchers from Dark Souls). Stay clear of the huge axe, dodge the chain and make sure to time your parries just right. Once she is down, carefully move forward and grab the Madman's Knowledge on a body to the left, behind a cage.
There are huge pits just beyond the Chief Attendant, so watch your step as you cross through the room. Behind a pillar is another Attendant, and to the right around a wooden screen is yet another wielding a crossbow that inflicts rapid poison damage. Two more lie in wait just past him to the left, along with another Chief Attendant. Fight them one at a time, being mindful of the pits, and continue on to another lift - but before using it, head to the left of it to grab a pair of Lead Elixirs.
Up the lift, you'll emerge into an open area outside the castle. To the left you'll spot some truly bizarre enemies - crows with the heads of dogs, and a dog with the head of a crow. Strange as they are, the swapped heads change only the sounds they make when attacking, so deal with them swiftly and walk up the stairs to the right. Go right as soon as you reach the top to see a hanging cage containing an item and another dog-headed crow. Roll into it and quickly kill the crow to nab a Tampering Damp Blood Gem (5), then return to the stairs and keep going. Head forward, watching out for a pair of crows waiting to drop on you from above, and you'll see another pair of levers and an open cage with a button on the bottom. Hop inside and drop down below to activate another shortcut from the Mergo's Loft: Base lamp.
Coming back from the shortcut, you'll see a doorway to your left, but don't use it just yet. Head down the stairs to your right, instead, and you'll find two more crow-headed dogs guarding some treasure. Grab the Blood Stone Chunk and the Kin Coldblood (10) off the two bodies, then go back up the stairs and through the doorway you passed earlier. Go across the bridge and you'll meet another new enemy, the skeleton marionette. These guys are ridiculously fast, but they spend most of their efforts dodging your attacks rather than launching their own, though they can still flank you very easily and catch you off guard. The corridor to your left only leads back to the start of the bridge, so steel your nerves and get ready to go through the door and face Micolash, Host of the Nightmare!
After the fight, go through the area and pick up some of the items you may have missed - you'll want to make sure you find the Iron Door Key, at the very least, but you can also find some Quicksilver Bullets, 4 Blood Stone Chunks (1 off of a body, 3 more off of a Scurrying Beast), another Kin Coldblood (10), and 3 Sedatives throughout Micolash's maze. Head out of the top of the maze (where you found the hole to drop down and finish Micolash off) and you'll see that the bridge has now been lifted and you can head over the Mergo's Loft Middle lamp. It's highly advisable that you equip as much frenzy resistance as you can, if you haven't already, because it's time to face the source of that orange light once and for all. The Deep Sea rune and the Graveguard Set (both available in Forbidden Woods) are invaluable here. Once you're ready, head straight from the lamp and into the next part of the level.
Finding the Blood Rock (From Mergo's Loft: Middle lamp)
Go up the stairs to the left and immediately turn to your right to find two Blood Stone Chunks guarded by two dog-headed crows and a crow-headed dog. Keep going up the long staircase and take another right, where you'll see a familiar green glow - another shortcut. Ride the cage elevator down to activate it, but keep an eye on the wall as you descend - you should notice an opening. Roll into it (don't go too early, or you'll splatter yourself on the ground below) and you'll find yourself in a secret passage. Head along it, and continue past the doorway to your left to find a chest with an Inflicted Organ in it. Return to the doorway and go through it. Here, you'll have to fight a Brain Trust on a long bridge. Remember, these things cause Frenzy to build up quickly as soon as it sees you, so watch its movement pattern and use the rocks on the bridge for cover. If you can sneak up behind it and get a charge attack in you can do a lot of damage without building up any Frenzy. Once you've killed it, carry on to the middle of the bridge and make sure to look to your right as you near the building at the end to spot a Kin Coldblood (11).
Keep moving, and you'll find a pair of Brain Trusts waiting for you. Don't try and take both on at once, instead, pull the one that is patrolling back to the middle section of the bridge, avoiding her grab attack all the way. You can use the structure in the middle of the bridge to break the line of sight if you happen to build up too much frenzy. Once she is down, sneak up on the stationary one and kill her as you did the first one. Once they're both down, head into the building at the end of the bridge.
There are four spiders in here. These are different to the Nightmare Apostles that you encountered earlier in the level as they have an AOE attack they can use if you don't kill them quickly enough. Kill the four spiders then head out out of the far end of the room and down the stairs. You'll spot a lever at the end of the next room, run across and activate it. You'll be treated to a cutscene showing the Brain Of Mensis being dropped into a bottomless pit. Once that's over, drop into the hole behind you (to the right facing away from the lever) and kill the two spiders. You can carefully cross the beams and kill the Brain Trust there if you want; you'll find a Choir Bell in the chest she is guarding. Whether you go for it or not, leave the building, where it's now safe to cross the bridge. Head across and grab everything you see - you'll find 4 Great One's Wisdom, a Madman's Knowledge, and a couple of blood gems. Once you've got it all, return to where the giant brain was and carefully drop down onto the stone path around the bottomless pit. On a body at the other side, you'll find the only Blood Rock in the main game (outside of the Chalice Dungeons), an item which allows you to bring a weapon from +9 to +10. Opposite the body you'll find a small hole in the wall which will take you back to the bridge where you fought the hunter, way back at the start of the level. From there, you can find your way back to the shortcut back to the Mergo's Loft: Base lamp and return to where you fought Micolash to continue on.
Getting The Final Moon Rune
Now that you've dealt with the Brain Of Mensis, you can get the final Moon rune. If you got the Blood Rock you'll be in the right place, in the area where you first encountered the Mergo's Attendants. Head down to the area where you encounter the first Mergo's Chief Attendant and you'll see that there is a new cage lift there. Kill the enemies, or sprint around them and get in the cage which will lower you into the darkness.
When the cage reaches the bottom, you'll be in pitch black (not unlike when you visit The Abyss in Dark Souls). Get out of the lift, equip your torch and go forward, eventually the Brain Of Mensis will come into view. Don't worry, it can't hurt you now. Approach its largest eye and use the Make Contact gesture. Hold it for about 30 seconds/1 minute and you'll eventually be granted the final Moon rune. Killing the brain is not difficult as it does not fight back, but it does have a large amount of health. Killing it will reward you with Living String, a ritual material necessary for the Great Pthumeru Ithyll Chalice Ritual, but leaving will not have any punishments.
Path to Mergo's Wet Nurse
From the Mergo's Loft: Middle lamp, head back to where you jumped down to get the Blood Rock, but instead of going right to the shortcut, take a left. You'll spot two Shadow Of Yharnam enemies. One with a katana and one with the candle and sword. They're not as strong as the boss versions encountered in Forbidden Woods so fight them as you would any other enemy. Once they're gone, continue up the stairs, being careful of the third Shadow waiting to throw fireballs at you from above. Past the third shadow, the path splits into three. The narrow path to the far left leads to a body with a pair of Blood Stone Chunks on it, the lower path leads to a dead end, and the path up the stairs takes you where you want to go next. There's a Maneater Pig waiting there with its back facing you, but don't get cocky - there are another two walking towards you just down the road. Rather than face them both at the same time, head down the street until they start walking, then turn around and hide near where you fought the first one. They should separate, allowing you to lure them out one at a time. Once both are taken care of, grab the Nourishing Damp Blood Gem (4), and the 2 Kin Coldbloods (11) to the left of the road.
NOTE: The pigs' charge attack deals massive damage to all characters in its path, and can be used strategically to dispatch other enemies. In other words, if you bypass the main road with the pigs by dropping down where the path branches, and take the waterway to the Bell Maiden, then you can flank the last group of Shadows. At this point, sneak back to the main road and agro the pigs, but do NOT let the pigs catch you--RUN as soon as they notice you, no later than they squeal to signal their charge. The pigs will bowl through the group of Shadows killing some and heavily damaging others, while the Shadows actually retaliate and kill the pigs with their powerful Chikage combos.
Further down the road, you'll spot another set of Shadows - four this time. Try to pull the three sword-wielding Shadows away from the one shooting fireballs, or you'll quickly find yourself overwhelmed. Once they've been taken care of, go to the left, down a flight of stairs, and engage two more Shadows. Defeat them, and you'll find the Chime Maiden for the second part of Nightmare of Mensis. Kill her and claim the 2 Blood Stone Chunks off a body nearby, but don't head back to the main path just yet. In this balcony area, you should find another set of stairs leading down into a flooded passage. Follow it, and you'll find a Scurrying Beast holding 3 Blood Stone Chunks (along with a spectacular view of the full moon).
Return to the main road now, and go up the stairs you passed to get to the Chime Maiden. At the top you'll find a sobbing woman in white: Yharnam, Pthumerian Queen. You can't do much with her now, so head down the stairs to her left (directly opposite where you came up) to find a chest holding Iosefka's Blood Vial. In the doorway nearby you'll find one last lift, this one giving you a shortcut from Mergo's Loft: Middle, and if you've been activating all of them as you've gone through Nightmare of Mensis, you'll now have a chain of lifts all the way from the lamp at the very bottom of the castle. Once you're ready, head through the door, enter the lift, and get ready to fight the final boss of Nightmare of Mensis, Mergo's Wet Nurse.
Credit to komachi-san
First lamp until the room of Micolash Micolash until Mergo