Okay, but how does the feminization magic work? Are there guidelines?

After being specifically asked about this, I've decided to include an excerpt from a conversation I had here to help clarify some things about the story.

"It's a little ambiguous and there's some wiggle room, but I'll lay out the generalities.

First of all, there are two separate things that are happening. First is the blood curse that was created in the ritual during the inciting incident of the story. This magic affects essentially every single elf and many of their allies that took part in the ritual. In addition to this curse/magic, elves may be subject to additional forms of magic/body modification more directly (think of the liquid that softens their teeth), some which might be permanent and some which might be temporary.

For the blood curse that affects all elves, it works like this: all elves will essentially experience significant feminization. Their feminine features and secondary sexual characteristics will be amplified and enhanced (larger bust, ass, hips, smaller waist, thicker lips, etc etc) and their masculine features will be reduced or eliminated (body hair, musculature, reduced penis size, etc). Elves will generally also experience mental feminization, reducing dominance, increasing submissiveness (especially sexual submissiveness), increasing desire to engage in receptive sex, increased attraction to the genitals of the monstrous races, etc. In addition, they will become more easily sexually excited, and feel more sexual pleasure from being penetrated, dominated and humiliated. In addition, "male" elves will tend to lose ability to become erect, perform sexually or enjoy using their penis in sex or be in dominant positions, and female elves will lose interest in having regular sex with male elves. "Male" elves will also broadly become impotent and lose fertility: their ejaculate will contain little to no sperm and they will have great difficulty impregnating anyone. At the same time, "male" elves will develop the ability to mother children via anal insemination. They gain the ability to be impregnated by the various "monstrous" races and bear, carry and birth their children. Such children will not be hybrids: they will be from the father's species, no elf genes or material will be passed on. Therefore most "male" elves will never pass on their bloodline.

The above effects apply to basically all elves and many of their allies. Some elves will be more affected by some parts of the curse and less affected by other parts, but for the most part they will all be affected by the whole thing.

Beyond what I listed above, their are also more specific forms of magic, surgery, body modification, etc that elves might be subject to. These could honestly be almost anything, whatever the group or individual in charge of that elf or those elves decides. It could be simple things that don't even need magic like castration, to something like the tooth potion, to advanced techniques like happened to Ethelid, who had most of their internal organs modified so that her captors could more easily use her for sex.

For the magic that is not part of the curse, I wouldn't worry too much about exact specifics or matching what I wrote, you can kind of have fun with it and write what is interesting to you. After all, their are many different "monstrous" individuals and they have different tastes and desires that they will modify the elves to."