Davick wrote:
There are also abilities that say "After you roll but before determining success." Do you have an ability that says, "After determining success but before [something]"?
Taking the rule that states, in uncertain terms, "The maneuver is successful and has the listed effect" to be the two happen at once is not a crazy idea. Trying to insert a point between two events described as simultaneously is, if nothing else, unnecessary. If it can be interpreted either way (and it definitely can), why would you take the interpretation that involves a theoretical break point somewhere? Forget K.I.S.S., use a little Occam's Razor here.
And again, being knocked prone is NOT an action. The only action the AoO can interrupt is you tripping them, but the AoO is not predicated on the occurrence of a trip as with the overwhelming majority of AoOs, but on its success. You cannot interrupt an action with an action whose success dictates the first action successfully occur.
SCENARIO:
A creature moves into your threatening reach and then continues to move again, outside of your reach. The movement (leaving a threatened square) provokes the attack. If your interpretation were correct you would get an AOO, but you could not reach them because they are now out of range.
A good example is the Pin Down Feat.
The attack you are granted must come before the 5-foot step resolves, otherwise the opponent would be out of range. (In most scenarios). The feat does not say explicitly say it occurs before the 5-foot is resolved, but it is understood because this is how AOOs work.
The TRIP PARADOX from earlier is also equally silly. If you look at the scenario above and allow the hit, what happens if the hit kills the creature? Suddenly the creature falls prone in the square, which means it didn't leave the threatened square, meaning it didn't provoke, meaning it didn't die. *Mind Blown*
It's not a perfect system, but seems pretty clear what the rule is here. AOO resolves IMMEDIATELY after the trigger, but before the trigger resolves.
Here is my chart breaking down the steps in an Action. (people seem to like these...)
1. Initiate action. (say out loud, I'm going to do something.)
2. Apply Penalties for action. (-2Attack for Power Attack)
3. Roll Dice. (Wait for it...)
4. Determine success/failure. (DM tells you it hits, YAY)
5. Apply Benefits of action. (Deal Damage)
AOOs and immediate actions can take place after any step in this process.
Examples:
A. Trip w/o improved trip. AOO=1.5
B. Feat: Lucky Halfling. Immediate=3.5
C. Greater Trip. AOO=4.5
D. Vicious Stomp. AOO=5.5