For the most recent session of my Brightwater campaign, the heroes had cause to revisit a site they had previously explored in part. Several weeks ago in the height of Sea Season, the Gloranthan Spring and the time of the highest water levels in the River of Cradles region, they had been exploring their domain, walking and wading through a bog that makes up a significant portion of it, happened upon a mostly submerged ruin. They explored, much hampered by the water that covered all but the highest points, and among other things, resolved to return when the Zola Fel River had returned to its banks.

The exploring they did do was enough to convince them of several things:

1 - They were intrigued by the mystery there: No one knew the name of the city then, and why it was here, so far below water level. There looked to be ruins similar in style to those found in the Big Rubble, a massive walled wilderness within the remains of a ancient city that the modern city of Pavis huddles near. Reaserch later suggested that this was a portion of the city of Rob-Cradle, destroyed hundreds of years ago by giants who were outraged by the actions of its inhabitants, who grew rich by looting the massive magical cradles containing infant giants that made the trip from the home of the giants, down the River of Cradles (hence the name) to the sea. Apparently, so angered were some of the giants, that one or more of them hurled an entire neighborhood dozens of miles away.

2 - The place was infested with Chaos.They knew this because gorps rose to attack them whenever they entered the deeper water. Gorps are nasty formless blobs ranging from housecat-sized to that of a mammoth. They swim well, are utterly mindless, eternally hungry, and attack and digest their food with a potent acidic grapple. They are primal creatures of chaos, brought into the world by the chaos demon god Pocharngo, Maker and Unmaker, Formless Master of Corruption. Now the heroes did not know all that at this point, but they knew they did not like gorps in their domain. 

3 - It appeared that the ruins had been only partially explored at best. The wandering they managed brought them a number of found items that piqued their interest. Also, they met and defeated but could not destroy, a singularly creepy creature of chaos that had made a home and impromptu temple out of an old building. Was she worshipping Pocharngo? No. Possibly worse, she had corrupted the local River Horse spirit, “infecting” it with chaos through her worship. The heroes were not sure of the details of this situation either, but they knew that the spirit was having an effect on the entire area, and that Chaos could not be allowed to endure.

I present to you the back story and datafile for Ynkla, the chaos creature that inhabits the Sunken City. I reprint her background in the datafile, so that those who download it will have it, but you get to read it here first.

Ynkla's write-up also includes a modified map that I am using to represent the Sunken City. The map was by the talented Stormcrow135.. Mine has added annotations to make it easier for me to reference. The link takes you to the unaltered version. FYI, Ynkla and her Bad River Horse Temple are at #4 on my map, but you can put her elsewhere of course. Other creatures at home in the bog are dragodons, shovel-noses, terror birds, giant vampire crabs, or Old Jack, all ready for you, along with a bunch more, here.

Ynkla is a tragic and terrible figure, a Naiad tortured and twisted until she was utterly changed from the gentle soul she had been. She was captured some time ago by a cult of Ogres on an island upstream and tormented, then infested with chaos, very much against the her will. On effecting her escape, Ynkla wanted nothing more than to find peace and a quiet waterway to call her own. She found the Great Bog, explored it and was overjoyed to find an ancient center of power to the River Horse. She crafted a driftwood idol, and gave her power to the spirit, hoping to reinvigorate it.  

But the savagery of the Ogres, the taint of chaos, had broken Ynkla. Her devotion was “wrong,” her methods cruel. Unaware even of her crimes, she began kidnapping otterfolk and newtlings, even the occasional elf of Deep Well, sacrificing them in terrible rites, hurling their power and her imprecations across the Veil into the spirit world, where the the River Horse could not help but hear.  River Horse, from his place in the spirit world, could not act directly, and was slowly perverted into a horrid chaotic hippocampus that became increasingly eager to answer her call.

And there were other things that felt that call. Gorps, mindless things drawn to chaotic locales, traveled the waterways to her temple. Mudsharks, terrible half-men with an appetite for human flesh, began to swim upriver from the sea to sport in the river and swamp. In this time, Ynkla became completely lost in what she had become, barely recalling any other life. The sunken city became a place to shun.