Editing Planes of Existence (section)

== The Prism ==
The Prism is not a plane, but a divine shell that surrounds the Inner Planes and separates them from the Astral Sea and the Outer Planes. It was constructed by a concordance of gods for two reasons: one, to prevent divine influence in the Plane of Things and vice versa, and two, to imprison the primordials, preventing them from reaching the homes of the gods.

The Prism can be passed through by mortals (though it’s very difficult to do so), but many divine beings are not allowed to bring their full essence through it, lest they warp the inner planes or accidentally release one of the primordials. Gods are allowed to project an avatar of themselves into the Inner Planes, however, but they are not allowed to interfere directly with the designs of mortals.