Slightly OT...
...but since we're talking about Power Attack in 3.5E...
I just started playing an acrobatic fighter/rogue armed with a guisarme. A reach/trip/smack/tumble/please-don't-hit-me-I'm-not-a-tank kind of warrior.
Seeing as he's wielding a 2-handed weapon, the new Power Attack is a no-brainer. But how does Power Attack work when my attack sequence goes Trip - normal attack -possble AoO if target stands? Power Attack as written states that I have to activate it on my action --does that mean I have to take the to-hit penatly on the Trip, if I want it to be in effect for the potential follow-up swing? And related to that, could I use Power Attack during an AoO? Would I need to have declared using it prior to any opponent provoking an AoO? Could I choose to activate PA for the AoO? What if moved 15' toward a group of enemies than waited for them to enter my reach --looking for attacks on all of them via Combat Reflexes? Could I use Power Attack if I don't make an attack and choose to wait for the AoO's?
Any clarifications/suggestions would be appreciated.