This is the new plane whose formation is described in the story I posted /forums/viewTopic.php?intTopicID=856, called the "Words of Change".
A strange rift in the Gray Waste opens up into what some speculate to be a new plane forming perhaps one day to be a new layer of the waste or perhaps even to join the others on the great wheel.
The plane is as yet un-named officially but is usually called "the growing plane of malice" due to the fact that it is growing and because of a feature nearby the rift from which it is forming. Overlooking the rift and the banks of the Styx branch that pours into the rift is the husk of a huge and apparently dead fiend partially covered in the dust of the waste. The husk radiates a palpable feeling of dread horror and overwhelming malice.
The Plane itself has been described as a bag of marbles with the rift opening on the Waste being the opening of the bag. Gravity initially goes down from the rift but gradually shifts to the wall of rock, earth and mettle that marks the boundary of the plane. The wall itself curves around in all directions like a balloon, and is continually expanding. The plane beyond the boundary wall is a void filled with spheres of stone and earth that have grown out of the wall itself separating as the wall expands. There are several new spheres forming in stages ranging from simple mounds on the flat wall to nearly separate spheres with their own gravity connected to the wall only by the last bit of stone and earth. It is at these new spheres that the growth of the plane can be directly seen as the spheres form out of the almost flat plane like bubbles on the surface of a pot of dishwater. It is at these new spheres that the growth of the plane can be directly seen. At some points the growth is visible daily.
Currently the plane has twenty two free floating spheres with the four largest in the center arranged in a pyramid (envision one sphere at each of the points of a d4). Each of these four spheres shows signs of volcanic activity and each are of sizes comparable to the larger Acheronian cubes. There are no volcanoes on the spheres' surface yet; instead the spheres tend to form fissures and sulfuric hot-springs. This is in stark contrast to the void between the spheres which is extremely cold. The void is not empty; it is filled with ice and snow formed from the Styx water that falls into the rift, and the debris from the rift and volcanic activity on the larger spheres. This means that there is the constant threat of that debris raining down onto the surface of the spheres or the border planes.
Other than some razorvine that has taken root in the harsh environment, there is little in the new plane, as of yet, in the way of flora and fauna. Most of the inhabitants of the plane have come in from the waste. The Fraternity of Order has established a base camp, named "The Planar Formative Analysis and Survey Team Primary Camp" or just the "Surveyor's Camp," on the largest of the four central orbs to survey and explore the plane. This has become the largest settlement and is quickly growing with an influx of explorers and mercenaries quick to come and risk their lives to learn and gain from the new plane. Already the larger spheres have each seen their share of battles as fiendish armies from both the Taanar'ri and Baatazu come to lay claim and build outposts in the new territory. Though all these battles have been recent, each occurring in the last twenty years after a plume of smoke shot out of the rift on the planes of the Waste. After that the Guvner's came to survey the plane and the rumors around their expedition spread to the players in the Blood War. The plane itself has been forming for thousands of years already but has been kept a dark by those loths, and night hags that have been exploring the plane on their own.
As far as native inhabitants to the plane the 'Guvners have already found a few rare specimens but the only inhabitants of any abundance, and even they are rare, are the new petitioners of the plane appearing similar to the larva that roam the waste but with bodies of squids rather than worms.