What we know (from the book blurb)
Taphos is the serpent-ruined island the Oracle points Nyx toward in Lamia’s Claim. A moon-lit temple and what lies under it are central to the rite with Seraphis and the lamia’s clutch. More geography and history will be filled in a later pass.
Related
See the Lamia’s Claim book page, the Monster-Breeder Saga hub, and the character pages for Nyx and Seraphis.