By manipulating the ambient light level, you can decrease or increase the illumination of an area. The change in illumination can be gradual (taking as long as 1 minute) or sudden (occurring immediately when you manifest this power). You can alter the level of illumination from its original level at any time during the power's duration.
You can decrease the illumination of an area by as little as 5% (barely perceptible) or as much as 100% (total darkness). If you decrease the light by 50% or more, the visual ability of creatures that depend on light to see declines accordingly. If you decrease the ambient light in an area by 100%, even those with low-light vision are unable to see within the affected area. For each 25% decrease in ambient light, characters in the area gain a cumulative +1 circumstance bonus on Hide checks (to a maximum of +4 when all the light is gone).
You can increase the illumination of an area by as little as 5% (barely perceptible) or as much as 100%. If you increase the light by 50% or more, the visual ability of creatures that depend on light to see improves accordingly.
You can use this power to increase the illumination of an area by 200% (improving visual abilities accordingly), but in such a case the power's duration is only 1 round.