Old School for Younger Readers!

[Norgarth]

Hmm. One decent one I can't remember the title of offhand, had Sailor Mercury swept into the Dungeon Keeper universe...as a Keeper. Had some interesting elements of her having to deal with the 'forces of  good' in the DK setting, as well a links back to the Sailor Moon setting...including things like Jadeite ending up as her assistant.

Dungeon Keeper Ami
https://forums.sufficientvelocity.com/th...per.31639/

Originally on the Anime Addventure before it died, now on SV (maybe SB, I don't know), last update was May 2021.
The thread itself is still semi-active.