Balance-Keepers

More myth than anything else, Balance-Keepers (or simply Keepers) are wraith like sinister spirits who will show up to mages playing with dangerous forces and strike them down, to keep the scales of the universe in line. They are considered to be nothing more than a cautionary tale that tells young mages trying to peek behind the curtain of high magic too eagerly, that with power comes not only responsibility but also attention of beings out of scope of their little brains. That can tear them to pieces no problem.
Some consider them a part of Void, other claim them to be a side effect of dark magic, while others think they are aspects of a long forgotten god of justice. Be it as it might be, you shouldn't wish to meet them. Watch the shadows around you carefully, when casting.