Grus is a remote fringe world protected by the Rhel'Kaeli Protoss under the dictates of the Dae'uhl, specifically the Saven'Rii elite praetor guard. Grus has unique atmospheric properties caused by electrically active particles in its upper atmosphere. These particles are psionic conductors that allow the world to be shielded from entry upon being charged with large amounts of psionic energy. Because of this, Grus if one of relatively few unique shield-worlds.