The Turquoise Serpent (Patreon)

A sort of deification of the main subterranean river of Nimbus, it being the primary water source for the onene once they're driven underground.  It's usually depicted as a blue snake with feather-like antlers and a shining silver striation down the back which forks into several smaller ones, representing a river with multiple tributaries.  Its depictions often show it on a slab of turquoise given the bright blue-green color of the river's water from copper compounds in the stone below the water itself.