I managed to get her health really down but the context key still didn't light up so I couldn't use the bondage horse key. Does her pleasure need to be high for it to be prompted ?
Hm it doesn't seem to be working on my end.
Just to be clear on the steps : got out of cell, get at the "end" of the dungeon, get key from sleeping guard, free yourself, take bondage horse key, go to main dungeon room, fight Nellie, make her cum. If I understand you correctly, this is where I should have the context option, but it remain greyed out :/
Worked for me, might be a glitch on your end, but just to make sure, you have to use the erotic option until she takes health damage/cums. At which point you get the text: "Nellie came! She falls down, reeling from pleasure!" That is when the context option should appear, with the following option: "Bind Nellie"
That is how I beat Nellie. However, I feel like I should probably clarify, after getting the bondage horse key, you should do the following steps:
1) Go back to the room with the tied up elf, where you will find Nellie torturing her.
2) Get Nellie's attention, by attacking, or using erotic option.
3) Run from Nellie's, and keep running away at every time she finds you, while making your way to the room with the Bondage horse. (If you haven't used the heals from the prisoners at this point you should probably use them to top off your health.)
4) Arrive in the room with the bondage horse and move around to trigger the encounter with Nellie.
5) Use the erotic option until she takes health damage/cums. At which point you get the text: "Nellie came! She falls down, reeling from pleasure!"
6) Congratulations you win. :D You had a bit of help, but you won so who gives care :) I mean maybe your pride but what has it ever done for you... :( ... imma stop now :(.
Well ok now I understand why it wasn't working.
I was indeed attacking Nelly, but I never fled and went back to the room with the bondage horse. I went there once after getting the key, but I thought it was just so you could know what the key was for. In the main room, there is another bondage horse (right by the bottom door, if I remember correctly), so I thought you were able to tie her up in that room with it. :/
Edit : just tried, it worked this time ! Thanks for the tip.