Lord Zack's Planescape
Belierin is a layer composed mostly of bogs and marshes, with tangles of mangroves in many places. Only a few settlements exist here on rocky spurs above the level of the swamps, many with a cathedral-like lighthouse, which directs travelers through the mists to safety.
This layer is supposedly the prison of some unknown dangerous entity, possibly a large creature or denizen of the lower planes. What is known is that it is not uncommon for evil creatures to be sighted here and the guardinals are constantly fighting back attacks by evil forces here. \