The Shadows Cast
Stygians are the Glowing Caves mutated versions. Many of them are darker in color than the rest of their cousins. Often a bit more solitary than the rest of them, they rarely venture out of their underground habitats.
Ability Score Increase. Your Dexterity and Charisma scores increase by 1. This is in addition to the normal Ability Score Increase for nereids, meaning that the total increase is +2 Charisma and +1 Dexterity.
Bioluminescent Magic. At first level you can recreate the effects of the Light cantrip, targeting only yourself, as your luminescent spots glow in otherworldly blue radiance. When you reach 3rd level, you can cast the Enthrall spell once per day, replacing the audible effects with visual patterns on your skin and hair. Charisma is your spellcasting ability for these spells.
Darkvision. Accustomed to life in the inkiest of dark depths, you have superior vision in dark conditions. You can see in dim light within 60 feet of you as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.