Positive Sphere
The prime material plane splits existence in two - on one half the positive sphere, and the other half the negative sphere. Each holds a vast multitude of planes clumped together with no discernible logic and separated by the difficulty of passing through the material plane with planar magic.
Most view the planes of the positive sphere to be safer and more welcoming than those on the negative sphere, but their surface appearance can hide deadly dangers to the unprepared.
