5e: Attacks of Opportunity

Written by Ethan

Ethan is a storyteller, GM, and all-around nerd. He spends his time introducing all of his friends to D&D and creating hard magic systems for upcoming novels.

Combat in D&D can be a blur. Enemies and allies are running to and fro, fireballs are being hurled, goblins are getting cut in half, and the healer is desperately trying to keep everyone standing. In the commotion of combat, everyone is keeping a keen eye on the foes that surround them. If a hostile creature tries to leave your reach, you can take a special attack called an opportunity attack. How does that work?

An opportunity attack is a melee attack you make against an enemy that you can see leaving your reach. You use your reaction to make this attack and must use whatever you have in your hand. Ranged attacks do not count, and some perks and subclasses can add extra utility to these attacks.

So let’s elaborate on that, starting with the most basic and building upward.

What is an Opportunity Attack?

An opportunity attack (aka “attacks of opportunity” or AoO) could occur in many situations.

Fighting toe-to-toe with an enemy and, after realizing they’re outmatched, they decide to run away? An enemy’s trying to get past you to the squishy wizard throwing spells from the backline? Or is a creature targeted by a spell like Dissonant Whispers using its reaction to run away?

All of the above are times when you should consider using your reaction to take a swing. Remember that you only get one reaction between turns.

Regardless of why they are moving away, if they use their movement, action, or reaction to leave your reach, you can make an opportunity attack against them.

To avoid an opportunity attack, you must take the Disengage action. When you do this, you are carefully retreating and keeping your guard up so that enemies cannot take a free swing at you.

What Isn’t an Opportunity Attack?

An opportunity attack is triggered by someone using their movement, action, or reaction to try to leave your reach. The following instances do not provoke opportunity attacks.

  • An enemy moving from a space in front of you to behind you. As long as the path of their movement keeps them within your reach, it does not provoke an attack. It’s only when they leave, even if they re-enter on the same turn.
  • An enemy moving into your reach.
  • Spells like Thunderwave or abilities like the Battle Master’s Pushing Attack that can knock people back against their will. These usually explicitly state that it will not provoke an AoO.
  • Similarly, environmental effects such as explosions or gravity moving a creature.
  • When an enemy falls prone or stands up from being prone.
  • Making a ranged attack when an enemy is within 5 feet of you. However, you make the attack with disadvantage.

How to Make an Opportunity Attack

The first thing you (the player) need to do to be effective at making opportunity attacks is: listen. 

Pay close attention when the DM is describing what the enemies are trying to do. Avoid tuning out and jumping on your phone once your turn is over. If you don’t use a battle mat, this applies doubly so.

If your DM moves an enemy out of your reach and you miss it, chances are the opportunity to attack is gone. If you realize ten minutes later that you should’ve been able to get to make an attack, it’s going to slow everything down to rewind for you. Alternatively, your DM will just tell you it’s too late.

Suppose you’re paying attention and an enemy leaves your reach. You shout: “Opportunity Attack!” Perfect. To make this attack, you make a melee attack with whatever is currently in your hand. 

If you’re a ranged character or a spellcaster, you might not have a weapon in hand, in which case, you would make an unarmed strike against your enemy. For many spellcasters, though, this probably won’t do any damage, but there are feats to help with that.

If you hit, you roll for your weapon damage or deal 1 + your Strength modifier for an unarmed strike. 

Congratulations, you’ve successfully made an opportunity attack. But there’s much more to it.


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Using Your Reaction

Making an opportunity attack requires you to use your reaction

Each round of combat, you get one reaction, which refreshes at the start of each of your turns. If multiple enemies leave your space in the same round, you can only take an opportunity attack against one, with each decided as they leave your space.

Therefore, if a minion is running away from you, but you expect to make an opportunity attack against a much larger threat in the same round, it can be worth saving your reaction for them.

Moreover, opportunity attacks compete with other abilities that use your reaction. 

If you’re a spellcaster, you might want to save your reaction to cast Shield, Absorb Elements, or Counterspell. You should consider the reward of making the attack against the risk of not having a reaction later. 

If you’re a wizard with a negative Strength score, there is very little upside to making an attack because your unarmed strike will do 0 damage, even if it hits.

Conversely, if you keep track of when certain enemies have used their reaction for the round, you can confidently run away from them since they have used their reaction. 

A clever party can bait their enemies into using reactions to make an attack so that they’re not able to cast Counterspell in the same round.

Reach

Opportunity attacks are triggered when a creature leaves your reach. For most characters, your reach is 5 feet

On a battle mat, squares are 5 ft. This means that if someone is on the square next to you and they try to move to a square not next to you, they trigger an opportunity attack.

There are ways of increasing your reach, which will affect when creatures provoke an AoO from you. 

Suppose you wield a polearm (e.g., glaive, pike, halberd, or lance), your reach increases by 5 feet. Similarly, if you play a bugbear, your long limbs increase your reach by another 5 feet.

In such a case, a creature can move up to 15 feet away from you, and you still won’t get an opportunity attack against them. The inverse is not true; when you leave their reach, they can make an opportunity attack against you.

While this doesn’t sound like an improvement to your character, the feats that are covered below make this an effective strategy. 

However, remember that anything true for you is true for your enemies. If your enemies have a large reach, you can safely reposition yourself on the battlefield while staying within that reach.

For example, an adult red dragon has three melee attacks: its claw, its bite, and its tail. While the claw attack has a reach of 5 feet and the bite attack has a reach of 10 feet, the tail attack has a reach of 15 feet. Therefore, you would not provoke an opportunity from the dragon unless you moved further than 15 feet away from the dragon. If you pay attention to the reach of your enemies, you can safely reposition without provoking attacks.

Different Types of Movement

Can you make an opportunity attack against a flying creature? What about one that climbs up a wall? The answer is yes—unless there is a specific rule that negates this.

For example, if an Aarakocra flies over your head, attacks you, then flies 20 feet directly upwards, it does provoke an opportunity attack as it has still moved out of your reach. It does not matter what kind of movement is used and in what direction the person heads.

However, be mindful of exceptions. If you are attacked by an Owl that then flies away, this does not provoke an opportunity attack because the Owl has a specific ability called Flyby that negates this.

Feats

The following feats greatly affect your ability to take or avoid taking opportunity attacks:

  • Mobile: If you make a melee attack against someone, you don’t provoke opportunity attacks from them for the rest of the turn. This works even if your attack misses.
  • Polearm Master: Creatures provoke an opportunity attack when they enter your reach. When most monsters in the game are melee-focused, you will always use this.
  • Sentinel: When you hit someone with an opportunity attack, their speed becomes 0 for the rest of the turn, creatures who take the Disengage action still provoke opportunity attacks, and you can use your reaction to attack someone who’s attacking an ally next to you. 
  • War Caster: When someone provokes an opportunity attack, you can cast any spell with a casting time of one action instead of a melee attack. 
    • For most spellcasters, this makes taking an AoO a viable option since even cantrips scale with your level and remain a strong option throughout the tiers of play (More on that here). 
    • Bear in mind that ranged spells are at a disadvantage because your opponent triggers the attack while they’re still within 5 feet of you.
    • Eldritch Knights can use this to cast Booming Blade at their enemies who are about to run away and trigger the additional damage of the spell.

For added improvement, combine the above options. 

For example, if you take Polearm Master and Sentinel, enemies enter your reach when they are 10 feet away from you. Polearm Master allows you to take an opportunity attack against them. 

If you hit, the Sentinel feat reduces their speed to 0. If they have a reach of 5 feet, they are stuck 10 feet away from you and cannot attack you unless they have a ranged option.


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Class Features

  • Eagle Totem Barbarian: During your rages, creatures are so scared of you they have disadvantage on opportunity attacks against you.
  • Battle Master’s Maneuvering Attack: You command a creature to move away from a creature you’ve attacked. Your ally doesn’t provoke opportunity attacks.
  • Monk’s Step of the Wind: You can take the Disengage action as a bonus action.
  • Hunter Ranger’s Escape the Horde: Everyone has disadvantage on opportunity attacks against you.
  • Rogue’s Cunning Action: You can take the Disengage action as a bonus action.
  • Scout Rogue’s Skirmisher: When an enemy ends its turn within 5 feet of you, you can use your reaction to move up to half your speed without provoking an attack.
  • Swashbuckler Rogue’s Fancy Footwork: Similar to the Mobile feat, if you make an attack against a creature on your turn, they cannot take opportunity attacks against you for the turn.
  • Swashbuckler Rogue’s Panache: You can disable an enemy from taking opportunity attacks against anyone except you.
  • Storm Sorcerer’s Tempestuous Magic: You gain 10 feet of flying that doesn’t provoke opportunity attacks.

The Bugbear Cavalier: The Ultimate Opportunist

While there are many ways of making opportunity attacks worthwhile, there is one build that outdoes them all. This is what you need to do:

  • Play a bugbear: Your long limbs add 5 feet to your reach.
  • Weapons: Wield a glaive, halberd, or pike. Your reach is now 15 feet (in total).
  • Class Archetype: Play a Cavalier fighter
  • Feats: Take the Polearm Master feat
  • At Higher Levels:
    • At 10th level, your Hold the Line ability means that enemies provoke opportunity attacks from you when they move 5 feet while within your reach. Your reach is a 7×7 square with you at the center. If anyone moves within this square, you can attack them.
    • At 18th level, you gain the ability Vigilant Defender. With this ability, you don’t just have one reaction per round. Instead, you have as many reactions as there are creatures around you, and if they provoke an attack, you can take a swing.

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Conditions and Opportunity Attacks

How do certain ongoing conditions affect your ability to make or take opportunity attacks in battle? Here’s the list:

  • Blinded: If you are blinded, you cannot see someone leave your reach and therefore cannot take an opportunity attack against them.
  • Charmed: If the creature that moves out of your reach has charmed you, you cannot attack them at all.
  • Deafened: No effect; AoO whenever you want.
  • Frightened: You can still attack, but you do so with disadvantage if you can see the source of your fear. If you must run away from something because you are frightened, you provoke an attack.
  • Grappled: No effect on making an AoO. Your speed is zero, so you cannot provoke an attack.
  • Incapacitated: An incapacitated creature cannot take reactions and therefore cannot make an opportunity attack. While an incapacitated creature can technically move and provoke attacks, this condition is normally combined with the Unconscious or Paralyzed condition or an effect that specifies that your speed is 0 like Hypnotic Pattern.
  • Invisible: An invisible creature does not provoke opportunity attacks because they are not seen leaving someone’s reach. An invisible creature can make opportunity attacks.
  • Paralyzed: A paralyzed creature is incapacitated and therefore cannot take opportunity attacks. They also cannot move, so provocation isn’t an issue.
  • Petrified: Same as Paralyzed—no and no
  • Poisoned: While you can still make an opportunity attack, you do so with disadvantage.
  • Prone: You can make an opportunity attack while prone. However, you do so with disadvantage. If a prone creature tries to roll out of your range, you can make an opportunity attack with advantage. If you’re prone while they roll away, then it’s just a standard attack (advantage and disadvantage cancel out).
  • Restrained: A restrained creature can still make an attack, but it is with disadvantage.
  • Stunned: Same as Paralyzed. Can’t attack and don’t provoke.
  • Unconscious: Same as Paralyzed. Can’t attack and don’t provoke.
  • Exhaustion: This only affects your ability to make attacks after 3 levels of exhaustion, at which point you have disadvantage on all attack rolls and saving throws. We have a post on that here.

Summary

An opportunity attack (aka Attack of Opportunity (AoO)) is a melee attack made as a reaction when someone you see attempts to leave your reach. Many features of the game can change the effect of this attack.

  • You can take the Disengage action to avoid provoking opportunity attacks.
  • Any creature that is moved without using its movement, action, or reaction does not provoke an attack.
  • Pay attention to what your enemies are doing so you don’t miss out on making these attacks.
  • You only get one reaction per round, so make sure you use it most effectively.
  • A creature only provokes an opportunity attack if they leave your reach. While for most creatures, this is 5 feet. It can be much larger for other races and monsters.
  • It does not matter what type of movement is used to leave your reach—it will still provoke an AoO.
  • Many feats and class abilities make it easier to make or avoid opportunity attacks, and the cavalier fighter is the ultimate opportunity-attack-making machine.
  • If you cannot see the creature leaving your reach, you cannot make an opportunity attack against them.

The action economy in D&D 5e is incredibly important. Using your action, bonus action, and reaction makes a party much more effective in battle. Once you get used to making these attacks, you’ll start thinking about how you can best position yourself on the battlefield to protect your allies and defeat your foes.

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