One of my players really really really wants mermaids in our game once we resume in the fall. My first reaction was that mermaids are perhaps a bit precious, but on the other hand, who am I to say no?
In any case, I don't think my players are really liking my pet setting, so I think I might go for something a little bit more classic DnD.
The Coral-Spired City and the undine’s capital. It straddles the shore, with its greater area deep underwater. Land-dwellers who wish to do business with the Undine may converse with them in the Dry Quarter or on palace-barges off the coast.
The Obsidian City, built ages ago with long-lost volcanic magic. It has been claimed by the Never-been, malign deep-sea beings that also captured the undines’ goddess. It was abandoned nearly overnight by its inhabitants, so its wealth still remain, beneath crushing pressure and total darkness.
Cathedral of Catastrophe
Church of the undines’ (relatively) new patron deity, Rasp, the stone-headed god of calamity. Travelers willing to perform a service for the Disastrous Bishops can secure safe passage over sea, protected from both storms and the grasp of the Never-beens.
Enemies of the Undine
The Deep Sisters
Sea-witches skittering across the abyssal plain astride their spider crabs, bringing false life to whale falls and snatching the souls of drowned sailors. Include The Bathyal Ladies, Mother Midnight, Agony Aunt, the Hagfish Medusa, and the Angler Queen
Attack: 1d8 (claws) or 1d6 (bite)
Movement: 120’ feet in water, 10’ on land
Bathyal Ladies are warped cousins of the undine, with the lower bodies and jutting jaws of a viperfish. They are photophagic, able to snuff all light sources within 100 feet, gaining 1d8 HP per source in the process. This can raise their HP above its normal maximum value.
Hadopelagic un-gods that ooze out of cracks in causality at the bottom of the world. They captured the Glass City of Old Thalassa centuries ago, and the goddess of the undine with it. Their influence makes all but the most cautious sea travel impossible. Include The Sans Seraph, Terror Doll, The Rickets Merchant, The Murder Swan, The Wicked Unravellers
Attack: d4 (touch)
Wicked Unravellers are human-shaped holes in reality, appearing as dark silhouettes swathed in unravelling rags. On a successful attack, they destroy a single piece of mundane equipment. If the victim has none left, the Unraveller un-happens something else, like the victim’s name, memories, senses of taste, or color. Wicked Unravellers move in water as easily as land.
The Blue Queen
Ancient undine and last surviving priestess of their nearly forgotten goddess. She is a mostly benevolent tyrant, but has no tolerance for anyone that risks breaching the security of her city. She has many agents across the continent, all of whom are eager to put ambitious adventurers to good use. Her plans to reconquer Old Thalassa do not necessarily square with the interests of land dwellers.
Priest of Rasp with an apocalyptic bent. Lives in a human village, trying to root out a diabolist that has been sickening livestock and ruining crops. He will reward anyone willing to help, but he is very tight-lipped about his past in New Thalassa.
Undine, a class for LotFP
HP and Saves as Cleric, XP as Magic-User
Undine have the upper body of a human and the lower body of a fish. Because their tail is powerful and nearly serpentine, they can move normal speed on land and in water. They can breathe both air and water, as well.
An undine can sing to put enemies to sleep. An undine’s song can affect anything that hears it.
When a target hears an undine’s song, they must make a Save vs Paralysis with a penalty equal to half the undine’s level. If they fail, they fall motionless until roused or they succeed another Save vs Paralysis, which they can make every round.
An undine can affect a number of HD of enemies equal to their level with a single song. Singing requires complete concentration; an undine cannot move or make any other action on the turn they sing.