Perception is a new 2.Neal satat that takes surprise adjust from Dexterity and illusion immunity from Intelligence.
Reaction Adjustment modifies the die roll to see if a character is surprised when he unexpectedly encounters NPCs. The more positive the modifier, the less likely the character is to be surprised.
Illusion Immunity is gained by those with exceptionally high Perception scores. Those with the immunity notice some inconsistency or inexactness in the illusion or phantasm, automatically allowing them to make their saving throws. All benefits are cumulative, thus, a character with a 20 Perception is not fooled by 1st- or 2nd-level illusion spells.