Vylja's Drow Alarm
(Invocation)(Protection)

Range:  10 yards
Components:  V, S, M
Duration:  1 hour per level
Casting Time:  1 round
Area of Effect:  30-foot radius sphere
Saving Throw:  Special

When a priest casts Vylja's drow alarm, he creates a magical dweomer in the area of effect which is tuned to the radiation given off by some creatures and objects of the Underdark, especially dark elves. If the dweomer detects such radiation in the area of effect, it triggers an alarm (either the booming sound of alarm-bells which can be heard up to 1 mile away, or a loud beep in the caster's head - the caster determines which at the time of casting). If no such radiation is detected, the spell expires after one hour per level of the caster.
The area of effect is sphere with a radius of 30 feet, and it is stationary for the full duration of the spell. The dweomer only reacts to the radiation that is given off in certain places in the Underdark. As drow use this radiation to craft their special gear, and as they need it to power their innate abilities, it is highly unlikely that evil drow will attack the caster without these advantages. Drow that enter the area of effect are allowed to roll for their magical resistance and then to roll a saving throw versus spell to avoid triggering the alarm; their items, however, are allowed neither and will thus automatically trigger the alarm. Note further that any item that gives off such radiation, even when carried by a non-drow will trigger the spell.
The material component needed for this spell is some dust that was subjected to the Underdark radiation. It is consumed by the spell.

