Helpless Defenders

A helpless foe-one who is bound, sleeping, unconscious, or otherwise at the attacker's mercy-is an easy target. A character can sometimes approach a target who is unaware of his or her presence, get adjacent to the target, and treat him or her as helpless. If the target is in combat or some other tense situation, and therefore in a state of acute awareness and readiness, or if the target can use his or her Dexterity bonus to Defense, then that target can't be considered unaware. Further, any reasonable precaution taken by a target, including stationing bodyguards, placing his or her back to a wall, or being able to make Spot checks, also precludes catching that target unaware and helpless.
Regular Attack
A helpless defender has an effective Defense of 5 + his or her size modifier. If a character is attacking with a ranged weapon and is not adjacent to the target, the character can use a full-round action to make the attack, and gain a +5 bonus on the attack roll. If the character is attacking with a melee weapon, or with a ranged weapon from an adjacent square, the character can use a full-round action to deliver a coup de grace.
Coup de Grace
As a full-round action, a character can use a melee weapon to deliver a coup de grace to a helpless foe. A character can also use a ranged weapon, pro-vided the character is adjacent to the target. The character automatically hits and score a critical hit. If the defender survives the damage, he or she still must make a Fortitude save (DC 10 + damage dealt) or die.
Delivering a coup de grace provokes attacks of opportunity from threatening foes because it involves focused concentration and methodical action.
A character can't deliver a coup de grace against a creature that is immune to critical hits.
Knockout Blow
As a full-round action, a character can make an unarmed attack or use a melee weapon that deals nonlethal damage to deliver a knockout blow to a helpless foe. A character can also use a melee weapon that deals lethal damage, but the character takes a -4 penalty on any attempt to deal nonlethal damage with the weapon. The target has an effective Defense of 5 + his or her size modifier. If the character hits, he or she automatically scores a critical hit (see Nonlethal Damage).
Delivering a knockout blow provokes attacks of opportunity from threatening foes because it involves focused concentration and methodical action.
A character can't deliver a knockout blow against a creature that is immune to critical hits.