Attack of Opportunity

Attack of Opportunity

Sometimes a combatant in a melee lets her guard down or takes a reckless action. In this case, combatants near her can take advantage of her lapse in defense to attack her for free. These free attacks are called attacks of opportunity.

Threatened Squares

You threaten all squares into which you can make a melee attack, even when it is not your turn. Generally, that means everything in all squares adjacent to your space (including diagonally). An enemy that takes certain actions while in a threatened square provokes an attack of opportunity from you. If you're unarmed, you don't normally threaten any squares and thus can't make attacks of opportunity.

Reach Weapons

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 threaten more squares than a typical creature. In addition, many creatures that are sized-large or larger have a natural reach of 10 feet or more.

Provoking an Attack of Opportunity

Two kinds of actions can provoke attacks of opportunity: moving out of a threatened square and performing certain actions within a threatened square.

Leaving a Threatened Square

Moving out of a threatened square usually provokes attacks of opportunity from threatening opponents. There are two common methods of avoiding such an attack — the 5-foot step and the withdraw action. Note that moving into a threatened square does not provoke an attack of opportunity, only leaving a threatened square.

Performing a Provokative Act

Some actions, when performed in a threatened square, provoke attacks of opportunity as you divert your attention from the battle.

Remember that even actions that normally provoke attacks of opportunity may have exceptions to this rule.

Note that a single action, such as a move action, can never provoke more than one attack of opportunity per enemy creature provoked, even if that creature is capable of making more than one attack of opportunity per round. For example, if you move in such a way that you are leaving more than one square threatened by the same enemy, you only provoke from that enemy a single time, because you only took one move action. Note that this "one attack of opportunity per action performed" rule applies per enemy, meaning that multiple enemies can each perform an attack of opportunity on you, if provoked, per action you perform which provokes. A full attack action is also considered a single action, for purposes of provoking an attack of opportunity, even though it could technically be severed.

Making an Attack of Opportunity

An attack of opportunity is a single melee attack, and most characters can only make one per round.

You don't have to make an attack of opportunity if you don't want to.

The to-hit roll of an attack of opportunity is always made at your highest attack bonus, even if you've already attacked this round.

An attack of opportunity "interrupts" the action of the creature which provokes the attack, meaning it is resolved immediately. Only if the provoking creature survives the attack can it finish performing its action. In most cases, actions which are interrupted by an attack of opportunity can only be stopped by reducing the acting creature to 0 or fewer hit points. The attack of opportunity itself does not prevent the action from occurring, nor does it (usually) inflict any penalties on the action.

Attacks of opportunity are only basic melee attacks. You cannot use a combat maneuver, cast a spell, or make a ranged attack as your attack of opportunity, unless you have an ability which specifically allows you to do so.