As soon as you enter the seemingly arena, you will immediately hear a baby’s cries. And the minute you interact with the baby carriage, the enemy shall make itself visible. You shall now battle Mergo’s Wet Nurse.
The Wet Nurse is a huge beast that has several arms and legs of blades surrounding it. As soon as it appears, it will take the carriage with it to protect it.
The Wet Nurse moves slowly and spins around with its blades in toll. The best thing you may do is to make use of the short time delay you have whenever the Wet Nurse slams its blades on the floor. Once you find an opening, try your best to get access to the its back and charge attack it from there.
Aside from walking around with its blades, the Wet Nurse will also summon a purple haze around her where several other clones of the Wet Nurse may attack you—so keep moving all the time. Once you are have successfully beaten the Wet Nurse and have indeed slain the Nightmare, you will be awarded with One Third of Umbilical Cord. From here, the only thing left to do is to teleport back to the hunter’s Dream and choose your own “ending”.