原文：
Attacks of Opportunity
The melee combat rules assume that combatants are actively
avoiding attacks. Sometimes combatants in a melee let their
guard down. In such cases, other combatants nearby can take
advantage of the lapse in defense to attack for free. These free
attacks are called attacks of opportunity.
THREATENED SQUARES
If you’re considered armed, you threaten all squares into
which you can make a melee attack, even when it isn’t your
turn. That usually means everything in all squares adjacent to
your space, including diagonally. An enemy that undertakes
certain activities while in a threatened square provokes
attacks of opportunity. If you’re considered unarmed, you
don’t normally threaten any squares and thus can’t make
attacks of opportunity. Certain conditions in combat, such
as concealment and cover, also affect your ability to make
attacks of opportunity.
Reach
Most creatures of Medium or smaller size have a reach of
only 5 feet. This means that they can make melee attacks
only against creatures up to 5 feet (1 square) away. However,
Small and Medium creatures wielding reach weapons might
threaten more squares than a typical creature. Creatures larger
than Medium have a natural reach of 10 feet or more, so they
threaten all squares within that reach, including diagonal ones.
Creatures smaller than Small typically have a natural reach of
0 feet, meaning they can’t reach into adjacent squares. Since
they have no natural reach, such creatures don’t threaten the
squares around them at all. See Size, page 116.
PROVOKING ATTACKS
OF OPPORTUNITY
Moving out of a threatened square can provoke attacks
of opportunity, as can being in a threatened square while
performing an act that requires focused attention.
Moving
Moving out of a threatened square usually provokes an attack
of opportunity from any opponent who threatens that square.
Two methods of movement allow you to avoid such an attack:
5-foot step and withdraw. See Movement, page 90.
Moving out of more than one square threatened by the
same opponent in the same round doesn’t count as more
than one opportunity for that opponent.
Focused Act
When you focus your attention on what you’re doing, you
divert your attention from the battle. The Actions in Combat
table, page 8, notes many activities that provoke attacks of
opportunity for this reason. Some such actions allow you
to make a Concentration check to avoid provoking (see
Concentration, page 33). Even actions that normally provoke
attacks of opportunity can have exceptions.
MAKING ATTACKS OF OPPORTUNITY
An attack of opportunity is a single melee attack you can make
when you’re active in combat and an opportunity presents
itself. If you’re fl at-footed, you can’t make attacks of opportunity,
and you don’t ever have to make an attack of opportunity
if you don’t want to. Making an attack of opportunity isn’t
considered an action, but you can make only one attack of
opportunity per round unless you have an attribute that
allows you to make more (see below). If you have multiple
attacks for some reason, you use your highest normal attack
bonus when you make your attack of opportunity, even if
you’ve already attacked during the round.
An attack of opportunity interrupts the normal fl ow of
actions in the round. If an attack of opportunity is taken,
immediately resolve that attack of opportunity, then continue
with whatever was happening when the attack of opportunity
was provoked.
Multiple Attacks of Opportunity
Some abilities allow you to make more than one attack of
opportunity per round. Most such abilities, unless they
say otherwise, don’t let you make more than one attack
for a given opportunity. If the same opponent provokes
two attacks of opportunity from you, however, you could
make two separate attacks of opportunity. Each provoking
act represents a different opportunity. Multiple attacks of
opportunity otherwise follow the rules for normal attacks
of opportunity.
