The Barrier
The Barrier is a magical dome that seals the Valley of Mines. It was created on the orders of King Rhobar II by twelve mages so that convicts forced to mine magical ore could never escape.
A One-Way Boundary
The Barrier lets information, weather, and objects pass in from the outside world, but kills any living creature that tries to cross it from the inside. Because of this, the Colony can still be resupplied from outside while the convicts remain trapped within.
A Failed Ritual
The mages' original plan was a controlled, localised dome. The ritual went wrong when the Sleeper, who had been disturbed deep beneath the valley, interfered with the weave. The result was a far larger and more unstable Barrier than anyone intended, and the mages lost all direct control over it.
The Circles of Magic
The mages responsible for the Barrier split into two groups inside the Colony after the ritual. The Fire Mages aligned with the Old Camp and the Crown. The Water Mages broke away to assist the rebels of the New Camp in hunting for a method to bring the Barrier down.