Sneak attack damage is granted by class and feat abilities, as well as a limited number of other character options, and always grants a number of bonus d6 damage dice. When a character possesses 1 or more dice of sneak attack damage, he may use them to augment the damage of each attack made against a target he’s flanking, or who’s helplessA helpless character is vulnerable. Further, attacks targeting him within Melee Range gain a +4 bonus. Finally, he may be targeted with a Coup de Grace action. or vulnerableA vulnerable character loses his Dexterity bonus to Defense (if positive), as well as all dodge bonuses to Defense. He may also be targeted with a variety of special effects, such as sneak attack damage. .
When sneak attack damage augments an attack’s damage, it is not applied separately; instead, it is added to the attack’s damage and they’re applied together as one result (e.g. when a character makes an attack with 1d8 lethal damage and may apply 1d6 sneak attack damage, the character rolls 1d8, scoring a 6, and 1d6, scoring a 4, for a total damage result of 10).
Unless otherwise specified, sneak attack damage may augment any attack — even an attack that inflicts subdual damage (in which case the sneak attack damage is subdual, not lethal).
Sneak attack damage may only augment the damage of a Standard Attack action.
Sneak attack damage may not augment the damage of any attack that’s converted from subdual to lethal, or vice versa.
Sneak attack damage may not augment an attack targeting a character who is immune to critical hits, who is hiddenA character or object whose location is unknown to 1 or more opponents is hidden from those opponents. An opponent may not physically target a character who is hidden from him with any action requiring line of sight or any skill check with the Vision tag. Further, when a character makes an attack against an opponent within Melee Range from whom he is hidden, the target is considered to be flanked, even if no teammate or ally is located on the other side of him. If the target is unaware that any enemies are present, he is considered vulnerable during this attack as well. Immediately following the attack, the character ceases to be hidden from the target. to the attacker, or whose vitals are out of reach (per the GC’s discretion).
Sneak attack damage may only augment an unarmed or melee attack, or a ranged attack against a target within CQB range. Beyond that, the accuracy required to hit the target’s vitals cannot be managed.
With each successful sneak attack, the target suffers 1 stress damage.
Action dice may not be spent to boost sneak attack damage.