I read Sigyn's Sigil by Megan Trotter. I'll write a more thorough commentary here than I sometimes do because this is self published by a local (?) writer and I expect you'll have difficulty sourcing you own copies. It wasn't even listed on Storygraph until I added it myself.

Last time I left the used book sale with a self-published book like this, I complained here about offensive restrictions on the copyright page. No such objections can be made about this book, and that's because it ... well, it doesn't have a copyright page. The front cover is nicely illustrated, the half-title page is autographed by the author, and then it's straight into chapter one. Not even a list of the author's other works, although I suspect this is a sequel to Sigyn's Song.

Sigyn used to be a mermaid, possibly one heavily inspired by HCA's Little Mermaid. Now in Sigil, she has fresh legs and lungs in her humanoid form. She also has the hots for the Norse god Loki, but is insecure about it because as a siren, she can make anyone fall in love with her and isn't sure if Loki's feelings are real or magic. Anyway, she and Loki are hanging out with Thor because he needs help getting his hammer, Mjollnir back from the giants. Apparently he mislaid it while whoring it up with some festival wench. The giant king is apparently willing to return it if Freya marries him, which isn't going to happen. So Loki shapeshifts Thor into the form of the goddess Freya, and himself into her handmaiden and the three 'girls' set off to trade her for Thor's hammer. Other than Sigyn's involvement, this plot line is from Thrymskvidha in the Poetic Edda, portions of which are excerpted for the chapter headings. Amazingly, they manage to pull this ruse off, despite the gods' unladylike behavior. Giant shaman Ymir knows the truth and doesn't out them, but isn't as helpful as they'd hoped although he seems to not want to get Sigyn killed for her part in this. They learn the hammer is hidden in the ocean, and Sigyn displays heroism and her mermaid background to recover it, while protecting the team from a deadly horse shaped water Nokk. Thor gets his hammer back and Ymir bestows Sigyn with a magic water sigil. They also liberated the Egyptian god, Set from Thrym's dungeon and might be setting up for a sequel involving him.

Romantasy isn't a genre I usually seek out, although I found this more humorous than erotic, and better writing and proofreading than some more commercially successful authors I've read. As appropriate for a polytheistic setting, the characters never say "goddamn", it's always "godsdamn". I wasn't sure what to expect from a book like this, but I think it satisfied my expectations anyway.