It's a Kamadan.
While I would love a Rod of Seven Parts adventure, Methinks it will be a Barrier Peaks adventure. That also sounds fun, and given the recent UA of Modern stuff, and this particular menagerie, I'll stick with Barrier Peaks until further notice. Its definitely a grognardiapalooza and one that hasn't really been re-done before in a meaningful way.
Or a touch of aberrant magic/mutants and all. Perhaps chaos magic? Something warping normal animals into these forms?