A creature who has not yet acted during combat is flat-footed, not yet reacting normally to the situation. A flat-footed character loses his Dexterity bonus to AC and Dodge AC bonus and cannot make attacks of opportunity.
Flat-footed characters are candidates for a rogue/blackguard sneak attack and/or assassin death attack. This applies especially when the character with sneak attack has much higher initiative than his/her opponent.
Notes
- The Dexterity AC bonus is lost when caught flat-footed unless you have the Uncanny Dodge feat.
- Dodge bonus AC is always lost when caught flat-footed.
- The Monk AC Bonus, and the bonus AC gained from Monk levels are never lost when caught flat-footed.
- AC gained through ranks in the tumble skill is always lost when caught flat-footed.