Creature Abilities
Source Alien Core pg. 208
The following creature abilities are listed here because they are shared by many creatures or are highly complex. The statistics for individual creatures might alter the traits, the number of actions, or other rules of these abilities. Anything noted in a specific creature's stat block overrides the general rules for the ability below. In these abilities, “monster” is used for the creature that has the ability, to differentiate it from any other creatures the ability might affect.
Darkvision
Source Alien Core pg. 208
A monster with darkvision can see perfectly well in areas of darkness and dim light, though such vision is in black and white only. Some forms of magical darkness, such as a 4th-rank darkness spell, block normal darkvision. A monster with greater darkvision, however, can see through even these forms of magical darkness.