I don't remember if it was a singular oneshot or a compilation of one shots but the one that remember the best is a Yuri story about a dungeon that makes people into monsters. I think it was two girls (I don't remember if they were friends or a couple) but one of the girls went missing inside and after years or months the protagonist goes inside with her team which ends up being killed by that missing girl (I don't remember if she becomes half octopus or half plant) and basically kidnaps the protagonist and takes her deeper into the dungeon where she "encapsules" The protagonist and it ends with the both of them having sex for well, the end of their days I guess?