The Black Mire

In the eastern portion of Ostoya, near the Dire Shore, a forest of aspens, willows, and oaks give way to fetid wetlands full of slow-moving, brackish water.
The Black Mire has not been thoroughly explored. Most cartographers are forced to turn back due to the treacherous terrain, bad weather, illness, or swamp monsters that accost them as they travel. Many an adventurer has met their end in the swamp’s murky embrace.

Stories persist that covens of hags dwell within the far reaches of the swamp, and that they are willing to make bargains with those who come searching for them.
One must beware when dealing with hags, however—often the payment they demand is something one is not willing to part with.