The River Heralds believe that the waters of the world are divided into two spheres: the river and the sea are the lower half, with the jungle and the sky above. They believe that the sea possesses an unfathomable wisdom, the deep musings of the unspeakably ancient world. But the wisdom of the sky and the rivers is embodied in the coatls—winged serpents that twist through the air to reflect the course of rivers along the ground.
Coatls are immortal guardians of the sky, dwelling always among the clouds. The River Heralds say that they can be enticed to the ground by the earnest supplication of the wisest of merfolk shamans. Coatls are said to be wise beyond mortal measure and incapable of speaking a falsehood, so their advice is often sought in times of desperate need. The sight of a coatl is thought to foretell favorable winds—a belief that has begun to spread from the River Herald shamans to the pirates of the Brazen Coalition. Use the couatl statistics in the Monster Manual for Ixalan’s coatls.