The Plane of Shadow is the one of the elemental Planes, the furthest from the beginning Plane of Life . It contains Mote Fields for Motes of Shadow , Motes of Fire and Motes of Air .
The ground consists of purple rock and Chasms are deep, foggy abysses. A purple haze permeates the air and there is no sunlight. The Shadow Plane's geography allows for large tracts of open land.
It is not possible to build Life structures on the Plane of Shadow.
The Shadow Plane contains Planar Portals to the Plane of Fire and Plane of Air .
The Plane of Shadow will at minimum be your fourth Plane, so this plane either presents or comes after your final elemental research tree. You already know what you're doing at this point, so you will be ready the complex opportunities provided by Shadow Logistics and Runeshrooms .
Those same complex opportunities also make the Plane of Shadow a good place to build in the late game, as everything Shadow provides can reliably be built. Without access to the renewable mote generation of Life , you will need to keep an eye on your resource pools, so Entropy technology will be useful here.