Board Thread:Speculation House/@comment-16348034-20130823234203/@comment-3146930-20130824200248

We've seen it from Crimson, Glynda, and Weiss, all of whom seem to be Dust users. One appears when Glynda calls in a hail storm to attack the airship. Crimson does it later to unleash a large blast that turns the debris Glynda was using to ash. These circles don't seem to appear when using Aura however.