I've got a player making a back-up character in case his current one falls to vampires. He is making a warforged Crusader/WF Juggernaut with the Stone Power and Shocking Fist feats. Shocking Fist is from Player's Guide to Eberron, FYI. The interaction of these feats will be brilliant, and with his delayed damage pool he can utilize it no matter the answer here, but the intricacies of the situation will determine exactly HOW useful it is to him.
First, some quotes:
Stone Power
When you use an attack action or full attack action, or you initiate a Stone Dragon strike in melee combat, you can take a penalty of as much as -5 on your attack rolls. This number cannot exceed your BAB. You gain temporary hit points equal to twice the number that you subtract from your attack rolls (to a maximum of +10). These temporary hit points last until the beginning of your next turn.
Shocking Fist
As a free action, you can channel some of your life force into a slam attack. You must declare that you are using this feat before you make your attack roll. When you use this feat, you deal damage to yourself (any amount equal to or less than your BAB). If the attack hits, you deal 1d4 points of electricity damage to the target per point of damage you dealt to yourself.
I imagine that my player is planning to take the -5 to hit and activate the Shocking Fist all at once, and the "damage" he takes will all be taken from temporary hit points produced from the attack roll itself (via Stone Power).
Q 581: Does it work that way? Or is there an order to it? IE - he can't deal the damage to the temp HP's because they don't exist yet, because he hasn't yet made the attack roll with the penalty. Or does it work, because it says the channeling of life force is a free action (and the argument would go, I'm sure...) which can happen as the attack hits, after the attack roll, even though you had to declare it before the attack roll?
Worst case scenario for my player is that round 1 he attacks, takes the damage (into his delayed damage pool) and deals the extra shocking damage, and then round 2 he takes a -5 penalty to get the temp HP's to soak the damage he will take at the end of the round from his delayed damage pool. Basically he doesn't use the DDP for its original intended purpose... he just uses it as a battery reservoir. That is 'always' full.
Edit: The delayed damage pool actually doesn't help in this instance, as it specifically says:
When you are attacked, any hit point damage the blow deals is added to your delayed damage pool.
So, the question becomes, can the temp HP's from a Stone Power attack soak up the damage incurred by employing Shocking Fist on the same attack?