So, after all this time I should know the answer to this, but I'm having a bad brain day and I can't remember the answer to this question: If a creature has reach and gets an AoO on an approaching creature (say a PC) does it get an AoO every round or is the attacking creature inside its reach and safe from the attack?
Just one time for moving "through" a threatened space in a single round (simply entering does not provoke).
No, the PC will not provoke every round - not just from being within the threatened area at least, but it does depend on what the PC is doing.
The PC will have to do something that provokes - casting a spell, moving more than a 5' step (which is what causes the initial AoO) etc.
Excellent. Thanks, guys! I should've known this, but some days anymore the neurons don't fire correctly.