Thlrun's Tracer

When this spell is cast, the lrace,......a continuous, luminescent pathway akin to a light spell-comes into being within a 10-foot radius of the caSler. It shows the most recent trail of any single creature whose path Ihe caster wishes to trace, described verbally by the caster over the material component (a pinch of phosphorus or a glowing life form such as a fungus or glowSpellbook, Wizard's Workbook r worm). The creature mUSI have been present in the IO-foot radius about the casler within a period of one day per level of the caster for the tracer to appear. Tulrun s tracer shows the route of the crealure within the I O-fOOl area, and then expands at a rate of60 feet per round along the route taken by the creature, moving in that direction for the duration of the spell. Once beyond the 10-foot initial radius, it only shows the trai l of the creature as long as il remains in physical contact with the ground. Pass without trace and similar spells do not confuse the tracer, and it will follow the creature's route through physica l barriers and across all gaps of up to 14 feet. It will nOI otherwise show aerial travel, but it does shine in and under water. The path ends when the target creature is rcached, the spe ll expires, or at any place to which the target creature leieported, left the plane of the caster, or embarked upon a mount or conveyance such as a cart, ship, or carpel of flying. In the laller case, an indi vidual reac hing the path's end receives a clear mental picture of Ihe deslination, even if on another plane. If the target creature look a mount or conveyance, the mental picture is of Ihe act of doing so and not of the eventual destination. Portions of the tracer can be negated by dispel magic, continual darkness, and the like, but it cannot be physically dislurbed (a gust of wind would not shift il). When the spell expires, the tracer slowly fades into nothingness; if it has not its target, there is no mental picture of the target's destination. The tracer is intangible, it may be passed through or traveled within without harm and does not activate magic upon contact nor does it distort magic or physical phenomena passing through it.

originally from Encyclopedia Magica Volume 4