Board Thread:Speculation House/@comment-16348034-20130823234203/@comment-10390252-20130824200057

Teravor wrote: Actually, so far we have only seen magic circles from Glynda and Weiss, and both times they were there to stop something (Or, in Weiss's case, to jump off of.)

They're not 'magic circles'. They're simply force discs of some kind.