False Swamp

https://bestiary.dragon-slayer.net/beast/562/gm
Isn't spreading currently. Not due to the efforts of Tarbreaker Juchin, a WA hired by the Black Brother to keep it at bay.
The creature spawned off a branch in Sunken Farahold. It was stolen by an adventure who later ran into a tackle eel; both were killed and the creature was let free.
When someone refuses to make a payment on their debt or pays off their debt, the qwibs of Huhli dir Syndi throw them into the False Swamp.