Fourth Layer of the Prison of the Multiverse (one of the Planes of Conflict)

Each orb is ~500,000mi from its neighbors.

Home to all manner of oversized and exotic beasts, gehreleth jailers, cunning hunters and raiders, and the souls of lying humanoids who harmed others in life with their falsehoods.

Every orb is covered in dizzying mountains (some hundreds of miles high), twisting gorges, and sheer cliffs. Rickety rope bridges and narrow footpaths facilitate risky travel between the handful of scattered plateaus and ledges, where the locals constantly battle for a place to rest without the fear of falling.

Travel to the previous layer above requires use of portals found atop some orbs' highest peaks. Portals to the next layer down can be found at the lowest points in canyons.

(Based on D&D 2E's Planescape material)