Not a story chapter, but the author of the completed "Mother of Learning" series (original fantasy time loop fic) has released an informational worldbuilding essay on transformation magics in the setting.
https://motheroflearninguniverse.wordpress.com/
https://motheroflearninguniverse.wordpress.com/
“I really hope I’m behind this convoluted mess; at least that way I’ll be able to get revenge by doing this to myself. I won’t even have to feel bad because it’ll be all my fault.” - Harry Potter, The Master of Death by Ryuugi.