Old Magick is a primordial magick greater than any other. It is that is neutral, it is power at its rawest. It is shaped by the intent of the Priestess who wields it. If her motives are not completely altruistic, chaos will be the result. A High Priestess has to banish all negative emotions: fear, anger, selfishness, vindictiveness, hatred, annoyance and frustration to be able to command and control Old Magick.
Old Magick has the power to set the balance between Light and Darkness. This form of magick has a volatile nature and a vampyre can only tell a High Priestess what not to do. In order for its power to work to balance and not corrupt, it must be commanded by a Priestess who is neither an aggressor nor a victim. Her intent must be pure and it can't be vindictive or destructive. The Seer Stone is not the only conduit for Old Magick; the tendrils of Darkness is also a conduit for Old Magick. They are too base and too raw to be anything but connected to the Ancient Powers of Light and Darkness. As long as there is Old Magick, there you will find the Fey.