The Totem of Nehual is something of a Maltese Falcon. Many have spent long periods of their life searching for it, spending vast sums of money, and in the end never finding it, or only finding it long enough to lose it.
The PCs find a small green glass bottle, something can be seen writhing within the smoked glass. If the PCs open the bottle a repulsing form of life will pour forth and grow in size. A genderless beings of soft pliable purple flesh towers before the PCs, it has no detail, no distinguishing characteristics except for a narrow slit for a mouth that holds rows of inwardly curving teeth.