Sea of Dreams
The munitions fired by the Arcane Gun. These are essentially specially treated sling bullets, which hold and deliver arcane energy in a devastating attack.
The Arcane are the only ones who know the secrets of creating Arcanus Rounds, but various other groups sell knockoff munitions at a discount. These cheap imitations do not deal as much damage as true Arcanus Rounds, and on a critical failure are liable to cause a backfire and destroy the Arcane Gun as well as killing the user.
An Arcanus Round can only hold its magical charge for one round before firing.