the Stone power feat (ToB, page 32) allows you to voluntarily apply a penalty to your attack rolls to get temporary hit points:
When you use an attack action or a full attack action, or initiate a Stone Dragon attack in close combat, you can penalize as much as -5 in your attack rolls. This number can not exceed your base attack bonus. You get temporary hit points equal to twice the number you subtract from your attack rolls (up to a maximum of + 10). These temporary hit points last until the beginning of your next turn.
Stone Power is clearly based on the Power attack feat (can even be treated as Power Attack by prerequisites). However, the power attack uses different words for its attack penalty:
In your action, before making attack rolls for a round, you can choose to subtract a number from all melee attacks and add the same number to all melee damage rolls. This number can not exceed your base attack bonus. The penalty for attacks and the damage bonus apply until your next turn.
If you are attacking with a single action (using the attack action or full attack, or initiating a single hit), awarding the stone power is simple: the penalty applies to all attacks that are part of the action.
However, it is possible to attack with more than one action during your turn:
- You could attack with your standard action, then use something like Celerity (PHB2, page 105) or a Battle Belt (MIC, page 73) to get a second standard action and use it to attack again.
- You could have a skill like Shadow Pounce (Unapproachable East, p.36) or the Sun School feat (CW, p.122) that allows you to attack when you teleport, start an attack with your Standard Action and then teleport with your Move or change the action (s) to carry out additional attacks.
- It could be something like a Choker or a 9th level Swiftblade that can naturally perform multiple standard actions per turn.
In cases like these, does the Stone Power penalty apply to everyone Your attacks for the round (like Power Attack), or only those that are done as part of the action in which you activated Stone Power?