|Mergo's Wet Nurse|
|Affiliation||Unknown (presumed as a Great One)|
|Locations||Nightmare of Mensis|
|Drops||One Third of Umbilical Cord|
Mergo's Wet Nurse is a strange towering creature with six skeletal arms and two black tattered wings. Strangely enough, the appearance of this being appears to be rather Pthumerian, despite its bizarre features, with its long, black, hooded dress and various jewels.
It has the power of creating a pocket dimension with multiple copies of itself and is able to teleport, but at close range it uses six curved swords with surprising speed and range as her limbs stretch out and spin in a devastating manner, shredding enemies who get caught in the flurry of slices.
Mergo's Wet Nurse is a being that guards the source of the nightmare, Mergo. Mergo is the child of Yharnam, who is standing outside the boss room. She will bow to the hunter if they go back the way they came after defeating Mergo's Wet Nurse, probably expressing gratitude to the one that saved or avenged her baby.
From Mergo's Wet Nurse's name we can conclude two things: it is female, and is serving as a surrogate mother to Mergo, attempting to nourish the infant Great One. It is unclear if the Wet Nurse herself is a Great One, but it does not seem like it.
Mergo's Wet Nurse is vulnerable to bolt, arcane, and poison attacks. Although she moves slowly, her multiple arms allow her to attack from any angle, even if the player stands behind her. The player should either stay at mid-range and bait her into using her slam attack or stay behind her and move away when she starts her blender combo. Although the initial strikes do little damage, they can stunlock the player and leave them unable to escape. This can be potentially fatal if they are low on health.
Mergo's Wet Nurse can be staggered relatively easily and this will interrupt her attacks if timed correctly. She will occasionally teleport away from the player before closing in with a lunging slash or stretching her arms. While these attacks can be evaded, they inflict massive damage if they connect. As the fight progresses, she will become more aggressive and chain her combos together, leaving less time to evade or retaliate.
When the boss raises its arms and summons a glowing orb, she is about to use her Nightmare Veil attack. This will cover the room in darkness, reducing visibility and making it harder to locate her. When she reaches 70% health, she will use a much more dangerous version of this attack that summons a duplicate of herself. This duplicate will chase the player around the room and will constantly interrupt them if they try to attack the real Wet Nurse. Whilst it can be momentarily destroyed with a single hit, it will continue to respawn until the nightmare veil wears off and it inflicts just as much damage as the boss. The player should sprint counterclockwise around the room and not slow down until the veil dissipates. As soon as the room returns to normal, the Wet Nurse will lunge at the player so they should be ready to evade immediately when the room brightens.
- Upon slaying the Wet Nurse, a Third Umbilical Cord will be dropped.
- Mergo's Wet Nurse is one of only three bosses that show the text "Nightmare Slain" instead of the usual "Prey Slaughtered." The other two are the Moon Presence and the Orphan of Kos.
- If Mergo's Wet Nurse is defeated during the nightmare realm phase, it will not show "Nightmare Slain" until the mist times out.
- If you defeat Mergo's Wet Nurse without allowing to enter mist phase, the health bar will remain on screen for some time after her death.
- If Mergo's Wet Nurse is defeated during its normal phase, it will not show "Nightmare Slain" until Mergo's cries are silenced.
- Using the Tiny Music Box during the battle will make the boss take a step back, as if recoiling.
- Various beasts and kin sport rags and weapons but Mergo's Wet Nurse attire and blades are far too courtly: it's well possible that this being was once a noble Pthumerian, twisted beyond recognition by the Great Ones power in order to be a conduit between them and the Pthumerian people (and expecially Yharnam, who was robbed of her child).
- Since both its wings and its arms are visible, it's not unlikely that its head is not exactly invisible but simply too alien and hideous to be perceived by a human mind.
- A wet nurse was a woman who would take care of a child in its infancy, sometimes even breast feeding it if the mother couldn't (possibly from death during childbirth, lack of capability in producing enough milk for the child, too busy, etc.)
- Mergo's Wet Nurse resembles the Grim Reaper with its black wings, swords that resemble a scythe blade, and a hooded head.
- Due to Mergo's Wet Nurse's reaction to the Tiny Music Box, which only occurs with both itself and Father Gascoigne, there is a likely connection between the two, the most common theory being Mergo's Wet Nurse is in fact Viola, Gascoigne's wife. This is further supported due to Viola's corpse disappearing from the Tomb of Oedon after Mergo's Wet Nurse is defeated. However, there is no certainty of this being true.