Pathfinder - The Inner Sea
Activate Class Ability: A character can spend one Action Point as a free action to gain another use of a class ability that has a limited number of uses per day. For example, a monk might spend one Action Point to gain another use of her stunning fist ability, or a paladin might spend one Action Point to make an additional smite attack.
Emulate Feat: At the beginning of a character’s turn, he may spend one action point as a free action to gain the benefit of a feat he doesn’t have. He must meet the prerequisites of the feat. He gains the benefit until the beginning of his next turn. For two Action Points, the character gains the benefit of the feat for the duration of the current encounter
Immediate Attack: When a threatened foe takes any standard, move, or full round action, a character can spend one Action Point as an immediate action to make an immediate melee attack against that foe. He makes the immediate attack at his full normal attack bonus — even if he’s already attacked in the round. An immediate attack “interrupts” the normal flow of actions in the round. If an immediate attack is taken, immediately resolve it. Then continue with the next character’s turn (or complete the current turn, if the immediate attack was taken in the midst of another’s turn).
Extra Attack: During any round in which a character takes a full attack action, he may spend one Action Point as a free action to make an extra attack at his highest base attack bonus. Action Points may be used in this way with both melee and ranged attacks.
Extra Move Action: As a free action, the character may spend one Action Point to gain an additional move action that round.
Negate a Condition: As a free action, a character can spend one Action Point to negate any one of the following conditions: dazed, dazzled, fatigued, shaken, sickened, or stunned. The condition is negated at the beginning of the character’s turn.
Negate a Critical: As free action even if it’s not his turn, a character can spend one Action Point to negate a critical hit scored on him by an opponent. This decision must be made before damage is announced.
Stabilize: Any time a character is dying, he can spend one Action Point to become stable at his current hit point total.
Action Dice: For one Action Point, a character can add two Action Dice to his Dice Pool. When the players makes any d20 roll, he can spend any number of Action Dice on that roll, up to the number of Action Dice in his Dice Pool. Each Action Die adds 1d6 to his d20 roll (including attack rolls, saves, checks, or any other roll of a d20) to help the character meet or exceed the target number. He can declare the use of Action Dice to alter a d20 roll after the roll is made, but only before the DM reveals the result of that roll. He can’t use Action Dice to alter the result of a d20 roll when taking 10 or taking 20.
Confirm Critical: As a free action, a character can spend one Action Point to confirm a critical hit without needing to roll for confirmation.