This is the origin of the Rifters and Outcasts in  Starhawk

The Union: better known as Rifters spread throughout  space conqueroring planets after planets for their most valued blue rift energy that is used for currency.

Outcasts: The Outcasts were once humans but unfortunately they were expose to the pure concentration of the blue rift that acted like a radiation mutating the once Rifters into a alien type creature that loves to fight and defend their rift territories from the Union. The oldest band of outcasts are the Shade warriors a fearsome clan of Outcasts that are more human like having the logic using their wits and their brutal methods of hit and run.