As the meme goes, "do you not realize how little that narrows it down?"
Assuming it was uploaded to FA mainsite and properly keyworded, you might still have to get a bit creative with your search queries ... one option might be the "tftg" (and/or "tgtf") acronyms, since FA search only works on keywords of at least 3 letters long (e.g. you can't just search "tg" directly). Obviously don't forget the "werewolf" keyword, but again, you are picking the number-one classic species for this so until you can find something more specific, you really are looking for a needle in a haystack here.
Since search by default looks at title, description, file name, tags, and probably a couple more things I forget, there’s a reasonable chance that “transform” or a variation could work (or maybe “into” though that probably has more false positives) - a lot of descriptions will include, from what I’ve seen, lines like “X transforms into Y” or “Z transformation”