Combat Expertise and Power Attack

[Hypersmurf]

I'd probably still limit it to BAB though.

As written, though, this isn't a restriction.

The 10th level fighter you described could put 5 points into Expertise, and still max out Power Attack at 10.

-Hyp.

 

[Caliban]

I have a Dervish PC with a Greatsword and Elusive Target who does this all the time.

He usually enters his dance, uses Combat Expertise for +5 AC, and Power attacks for 2 (gives him +6 damage due to his Armbands of Might). (Total of -7 to his attack.)

Then he moves past his opponent, deliberately provoking an AoO (but he's at +9 to his normal AC due to Combat Expertise and Mobility), and assuming the AoO misses he gets a free trip attempt on his opponent. If his opponent is tripped, the +4 bonus for attacking a prone opponent nearly cancels out the -5 for combat expertise, leaving him at a net -3 on his attack roll.

And he will usually end up more than 5 feet away from his opponent, meaning that they will have to stand up and move toward him, reducing them to either a single attack or no attack.

It generally only works once or twice against any given group of opponents, but that's usually all you need.

 

[Ranger REG]

Is there anything that would stop someone/thing from using both of these in the same attacks? I don't see anything that would.

Other than your BAB determining the most you can benefit from each of the two above (if you're willing to take a lot of penalties to your attack rolls), nope.

 

[Goreg Skullcrusher]

There is one reason to be cautious about letting people use both for a total penalty exceeding BAB. It's the "only hit a 20" case. Let's say you're going really defensive against a high-AC opponent. You're only going to hit on a 20 anyway, so you may as well Power Attack for full. In this case, you're not sacrificing ANY accuracy for the increased damage from Power Attack. Your chance to hit remains at 5%.

I had a player who did exactly this, and my response was to simply disarm him. He failed both the AoO and the opposed attack roll (the latter quite badly, as his to-hit roll was negative). Sunder would have worked as well.