Concealment

When making a melee attack against an adjacent target, your target has concealment if their space is entirely within an effect that grants concealment. When making a melee attack against a target that isn't adjacent to you, use the rules for determining concealment from ranged attacks. In addition, some magical effects provide concealment against all attacks, regardless of whether any intervening concealment exists. Concealment Miss Chance Concealment gives the subject of a successful attack a 20% chance that the attacker missed because of the concealment. Make the attack normally — if the attacker hits, the defender must make a miss chance d% roll to avoid being struck. Multiple concealment conditions do not stack. Total Concealment If you have a line of effect to a target but not a line of sight, he is considered to have total concealment from you. You can't attack an opponent that has total concealment, though you can attack into a square that you think they occupy. A successful attack into a square occupied by an enemy with total concealment has a 50% miss chance (instead of the normal 20% miss chance for an opponent with concealment). You can't execute an attack of opportunity against an opponent with total concealment. Ignoring Concealment Concealment isn't always effective. An area of dim lighting or darkness doesn't provide any concealment against an opponent with darkvision. Characters with low-light vision can see clearly for a greater distance than other characters with the same light source. Although invisibility provides total concealment, sighted opponents may still make Perception checks to notice the location of an invisible character. An invisible character gains a +20 bonus on Stealth checks. Varying Degrees of Concealment Certain situations may provide more or less than typical concealment, and modify the miss chance accordingly.