This spell causes a luminous glow within 20 feet of the spell's center. The area of light thus caused is equal in brightness to torchlight. Objects in darkness beyond this sphere can be seen, at best, as vague and shadowy shapes. The spell is centered on a point selected by the caster, and he must have a line of sight or unobstructed path to that point when the spell is cast. Light can spring from air, rock, metal, wood, or almost any similar substance. The effect is immobile unless it is specifically centered on a movable object or mobile creature. If this spell is cast upon a creature, any applicable magic resistance and saving throws must be rolled. Successful resistance negates the spell, while a successful saving throw indicates that the spell is centered immediately behind the creature, rather than upon the creature itself. A light spell centered on the visual organs of a creature blinds it, reducing its attack and saving throw rolls by 4 and worsening its Armor Class by 4. The caster can extinguish the light at any time by uttering a single word. Light spells are not cumulative—multiple castings do not provide a brighter light.
The spell is reversible, causing Darkness in the same area and under the same conditions as the light spell, but with half the duration. Magical darkness is equal to that of an unlit interior room—pitch darkness. Any normal light source or magical light source of lesser intensity than full daylight does not function in magical darkness. A darkness spell cast directly against a light spell cancels both, and vice versa.