Pathfinder 2nd Ed.: The Slithering - Rules of Play says:
The Slithering is a deluxe adventure for 5th-level characters written by Ron Lundeen. Featuring terrifying new monsters, repulsive new rules and magic items, and an in-depth look at one of the most exciting cities in the jungle-choked Mwangi Expanse, The Slithering provides a wealth of secrets and dangers!