This invocation causes an object to radiate shadowy illumination out to a 20-foot radius. All creatures in the area gain concealment (20% miss chance). Even creatures that can normally see in such conditions (such as with dark-vision or low-light vision) have the miss chance in an area shrouded in magical darkness. Normal lights (torches, candles, lanterns, and so forth) are incapable of brightening the area, as are light invocations of lower level (such as light or dancing lights). Higher level light invocations (such as daylight) are not affected by darkness. If darkness is cast on a small object that is then placed inside or under a lightproof covering, the invocation's effect is blocked until the covering is removed. You can only have one instance of this spell active at any given time, and if you use this ability while prior casting of this ability is still active, the prior casting of this ability disperses. Darkness counters or dispels any light invocation of equal or lower invocation level.