Here's a trick from Christopher's GM tool chest.  Play intelegent fighters intelegently.  IE, they know what provokes an AoO, and generally they try to avoid it.  The Skeletons could have run up to Kasumi's reach, stopped, then nex turn made a 5 foot step and attacked Kasumi.<br/><br/>Unintelegent fighters, or people in a hurry, tend to get knocked down by people like Kasumi, and that's alright.  Combat Reflexes is built to fight those people, the ones who figure, "If ALL of us charge her, most of us will get by." That's why it's a feat.<br/><br/>IMO, smart positioning and feats make the fighter efective, when all a spell caster has to do it cast a spell to acomplish something much better.