No one is quite sure what the Blue Glow is, magical remnant, extra-dimensional being, or time-space anomaly. It appears and disappears with no apparent pattern, showing up for a few minutes on one occasion, shadowing someone for days on another.
The Blue Glow appears to be nothing more than its name implies, a faint blue glow radiating from some hidden light source. The Glow varies in both size and shape, appearing as a single palm-sized area to several dozen glowing patches scattered over a hundred foot radius area. The source of the Glow is always obscured by some mundane object, the corner of a building, a tree or stone, or a piece of furniture. When it first appears the Glow is very faint, gradually gaining intensity as it remains undisturbed. If approached the Glow fades away, often reappearing in second spot even as the first fades.
The Glow's elusive nature make its characteristics very difficult to determine, an Epic test of divination magic may reveal the... whatever it is, radiates a sort of anti-magic, causing even a potent divination spell to quickly collapse upon itself. The Glow appears to have no physical manifestation, and whatever controls its form and function detects and avoids even the most potent forms of magical scrying. No one has ever seen whatever source produces the Glow, leading some to speculate that no such source exists. Magical defenses, such as warding circles and protection spells, seem to have no effect on the Glow. The only true defense seems to be rigorous observation of the surrounding area.
The Blue Glow has a singular unique property. If it remains in the vicinity (approximately 30 feet) of any magical effect for more than an hour it consumes one rank of magical energy from each device or source. All sources of magical energy are affected by this draining effect. In the case of items with charges or use limits, the Blue Glow reduces or permanently destroys a portion of the stored charge. In the case of permanently enchanted items, the draining effect is temporary, lasting one week per rank of energy drained. Note that living creatures can also be affected, causing magic using creatures or spell casters to temporarily lose access to their magical powers.
The Glow will remain in the vicinity of magical energy sources until it has drained 2d10 ranks of magical energy, then it will vanish, reappearing in a new location in 2d10 weeks.