Flat-footed is being especially vulnerable to attacks at the beginning of a battle. Characters are flat-footed until their first turns in the initiative cycle or after the first flurry of attacks by a single opponent against them, whichever comes first. A flat-footed creature loses its Dexterity, Tumble and Dodge bonuses to Armor Class (as well as penalties) and cannot make attacks of opportunity. Flat footed opponents are vulnerable to sneak attack. By default, Uncanny Dodge does not avoid losing these bonuses*
Characters are considered flat-footed only under the following circumstances:
- Performing a non-combat task.
- Not currently engaged in combat.
- Attacked by an undetected opponent.
- During the combat round in which they have been successfully feinted.
- If they are stunned, paralysed, or asleep.
* Uncanny dodge will avoid loss of Dexterity, Tumble and Dodge bonuses against invisible attackers only.