Kalloi is correct here, Smug and Used are extra to replace Joy and Lewd respectively depending on the girl's personality and corruption. Or if you like seeing your Chosen.... painted.
Well great, now I'll need to finish those.
Unsurprisingly, they're the most time consuming image to make... Aside from trying to get Reaper's civilian form to have the same haircut she did while transformed.
Trial and error and repetition. Basically I take the same prompt from one of the portraits, take out the "[...] background" and "portrait" tags, add NSFW if it doesn't already have it (very important, as it's blacklisted by default) add in "crowd," "multiple men," "group sex," (Even if you don't want multiple partners, "crowd," has been the easiest way I've found to get any people other than the subject) and "skirt" because the AI likes to get rid of a girl's clothes when she's having sex, for some weird reason. Who even does that?
After that, add any additional context you want that's specific to the scene; I usually put it out in one or two word tags to make it easier to fine-tune, but I've seen great results with natural language, so follow your dreams I guess. Then I just start generating images and tweaking the prompt until I find one I like, set that as the seed, and start messing around with the prompt until it's either perfect, or I can't be bothered anymore.
For example the one for Paladin I just uploaded had the prompt:
{{{magical girl uniform}}} {{{magical girl}}}, nsfw, lilac hair, {{green beret}}, blue eyes, short hair, crowd, multiple men, group sex, sex, hand on cock, sucking cock, holding cock, green skirt, facing viewer, white blouse, nipples covered, ahegao,
And that's been one of the easier ones. Often I'll need to repeat and rephrase something several times; I distinctly remember many of the Bonus images having tag lines with such winners as "multiple-penetration, sex, penetration, cock in pussy, ass sex, butt, butt sex, cocks, multiple cocks, three cocks," and then I'd fight it for half an hour because adding "open mouth" changed the girl's hair color, and "orgasm, ahegao," turned one of the men into a bowl of fruit or something.