I've recently started making a series of Monster transformation files - each one is about turning into a different monster from mythology or fantasy.
[url=https://www.warpmymind.com/index.php?gadget=HFiles&action=GetFile&file_id=13663]Drider[/url] is about turning into a half-spider person with eight chitinous legs, eight eyes and a huge spider abdomen complete with a spinneret. I might be making a more in-depth version with even more transformation such as mandibles, full exoskeleton, etc.
[url=https://www.warpmymind.com/index.php?gadget=HFiles&action=GetFile&file_id=13698]Milky Minotaur[/url] and [url=https://www.warpmymind.com/index.php?gadget=HFiles&action=GetFile&file_id=13699]Musky Minotaur[/url] are a pair of pay files that are about being turned into a half-bull Minotaur. One has breasts and udders, and focuses on a milking fetish, the other has a bull penis and rapidly-filling balls. Both have an extra fantasy segment afterwards of wandering in a labyrinth in order to reinforce the transformation trigger, and also to have some fun giving in to the urges of your new body.
Recently Hypnoslumber also released [url=https://www.warpmymind.com/index.php?gadget=HFiles&action=GetFile&file_id=13696]a minotaur transformation[/url], and there are many older files with a monster TF theme like the work of Tasha_Lynn (the kitsune file [url=https://www.warpmymind.com/index.php?gadget=HFiles&action=GetFile&file_id=12492]Foxy Fantasy[/url] and the Hathor's Cowgirl files being ones I'd recommend).
I've got some ideas for monster files I want to make - demon, harpie, merfolk, mimic, plant, slime and naga - but I'd love to talk about ideas others have.