Upon casting this spell, a neogi creates the illusion of thousands upon thousands of crawling spiders. Only a number of creatures equal to the level of the caster can be affected by this illusion, and all must be within a 10-foot diameter sphere. Any creature targeted by the spell must save vs. spell, success indicating that the spell has no effect. Any creature failing its initial save must save vs. spell again. Success indicates the creature flees from the area at its fastest possible movement rate for 2-5 rounds. Those who fail are so frightened that they are unable to do anything except try to remove the spiders they believe are crawling all over their bodies.
The illusion this spell creates is different for each individual. It might be argued that, for example, umber hulks have little to fear from spiders but when those spiders are 1 foot in diameter with armor-piercing fangs, there is much to fear. The neogi tend to use this spell to disrupt and disorganize enemy forces when boarding actions are taking place.
Note: Regarding the initial saving throw, DMs must decide whether the target creature has reason to believe that what he is witnessing is an illusion. It is not unreasonable to assign a beneficial modifier to the initial save roll if the target has reason not to believe in the illusory spiders.
Notes: Common for neogi; rare for drow; very rare for others. (Updated from Dragon Magazine.)