Create Darkness
As a standard action, the creature can create a 20-foot-radius area of darkness centered on itself, which negates the effects of all nonmagical light sources in that area. This darkness lasts for a number of minutes equal to the creature’s CR, and the creature can dismiss the effect as a standard action. The darkness doesn’t move with the creature. Unless otherwise noted, any magic source of light can increase the light level in the area as normal.
Format: Offensive Abilities create darkness.
Source
Alien Archive pg. 153