This spell is an improved version of skull watch used by necromancers with large, permanent bases. Like skull watch, the improved spell sets an enchanted skull either on a surface or hanging in midair. Living, intelligent creatures that enter an area 20 feet wide by 90 feet long in front of the skull cause the improved skull watch to activate.
The activated skull will scream, which can be heard up to a quarter-mile away. The activation also mentally communicates the presence of intelligent, living creatures to the caster, if the caster is on the same plane as the skull. The skull will communicate general visible data about those who have activated the warning device (race, appearance, visible weapons, and so forth, but not alignment, level, or magical abilities).
The wizard can create as many improved skull watches as he has levels. Each one sounds alike in its scream, but the wizard will know the location of the activated skull. Once activated, the floating skull sinks slowly to the ground and can be reused later.
Once the skull is in place it cannot be turned or moved. A dispel magic will deactivate the skull, as will destroying the skull itself. The skull has AC 5 and 2 hit points for every level of the caster. Destroying or dispelling the skull will cause the caster to be aware of its destruction, but not reveal the attacker's nature.
The spell requires the complete skull of a humanoid, intelligent creature. Its material component is a bit of earwax. Should a caster die before his skull watch areas are activated, they will still be in operation.
Notes: Uncommon for necromancers; otherwise very rare. In the Forgotten Realms setting, it is known to be in the book Tidings of Conflict and Woe.