Learn how reactions work and how to maximise their use
When playing D&D, you will often find yourself in combat situations. During these moments, what you can do is broken up into various actions known as your; action, bonus action, reaction and (possibly) lair action. On top of this, players will also be able to move as well. Within each of these action types are a plethora of options depending on your class, race, feats you’ve taken, spells you can access and even the type of movement you want to make.
As you can see, it can be easy to get bogged down in what you can do at any given moment. But we’re here to help with a guide that not only explains how reactions work, but also how to get the most out of your reaction.
What is a reaction and how does it work?
A reaction is one of the action types you can take during combat in D&D. Unlike other action types (apart from lair actions), it doesn’t occur on your turn but instead happens due to something else that occurs during another character’s turn. This could be an attack of opportunity when an enemy moves outside of your melee range, it could be a counterspell cast in response to another spell being cast or it could be an ability that lets you defend another character.
You can only use one reaction per round (a round being the period by which everyone completes a single turn) so if you’ve made an attack of opportunity, you can’t then cast counterspell in reaction to an enemy spell until you’ve completed your next turn.
Reactions can be extremely useful as while there are usually a lot of options associated with standard actions and bonus actions, the number of things you’re likely to do with a reaction are more limited. This can mean though, that they’re often under-utilised.
Common reactions and how they work
Opportunity attack
An opportunity attack can be performed when an enemy leaves your melee range (usually 5 feet but sometimes 10 feet). This normally happens when an enemy is attempting to flee from you or is moving past you. An enemy can move into melee range without instigating an opportunity attack but will instigate one if they move out of range.
The opportunity attack is a single attack (no extra attacks allowed for this reaction) with the melee weapon the character is wielding. An enemy can avoid an opportunity attack by taking the disengage action or through other abilities like being invisible.
Ready action
If you’re in a position where you can’t use your action in the desired way, you can choose to ready an action and use it as a reaction. By doing this, you prepare to do something you could normally use as a standard action such as make an attack or cast a spell, but this action will occur as a reaction when some other event happens that you declare, for instance, you could ready a spell to cast when the enemy opens a door or ready an attack to strike when an enemy comes into sight or range.
Spells
Some spells can be cast using a reaction. There are only a handful of these but usefully, unlike spells cast as a bonus action, you can cast a spell of any level using your action and can then cast a spell as your reaction of any level too. This is in contrast with your bonus action where you can cast a spell for this and your action, but one of these spells would have to be a cantrip.
We’ve included all the spells available in D&D 5e that can be cast as a reaction below:
| Spell | Level | Range | Duration | Classes | Description |
|---|---|---|---|---|---|
| Absorb Elements | 1st | Self | 1 round | Artificer, druid, ranger, sorceror, wizard | Half elemental damage received and add 1d6 of that damage type to your next attack |
| Feather Fall | 1st | 60ft | Concentration, 1 minute | Artificer, bard, sorceror, wizard | Slow falling speed of up to 5 creatures |
| Hellish Rebuke | 1st | 60ft | Instantaneous | Warlock | When damaged, cause 2d10 fire damage to your attacker adding 1d10 for each level higher you cast at |
| Shield | 1st | Self | 1 round | Sorceror, wizard | Add +5 to your AC for one round after being hit |
| Silvery Barbs | 1st | 60ft | Instantaneous | Bard, sorceror, wizard | Cause an enemy to reroll a d20 and take the lower result and give an ally advantage on their next roll |
| Gift of the Gab | 2nd | Self | Instantaneous | Bard, wizard | Replace something said in the last 6 seconds form someone’s memory with a different sentence |
| Counterspell | 3rd | 60ft | Instantaneous | Sorceror, warlock, wizard | Cause a 3rd level or lower spell to fail or make a spellcasting check of DC 10 + spell level |
| Temporal Shunt | 5th | 120ft | 1 round | Wizard | Cause an attacking enemy to disappear for 1 round, preventing their attack or spell |
Feats
Feats are abilities that can be taken by any character when they level up instead of taking an ability score improvement. Feats can provide all sorts of benefits and in some cases, can be used as a reaction. Below, we’ve detailed the feats that can be used with your reaction:
Defensive Duelist – When duel wielding and you’ve been hit by a melee attack, add your proficiency bonus to your AC for that attack.
Fade Away – After taking damage, you can use your reaction to become invisible until the end of your next turn. This can only be used once per rest.
Gift of the Chromatic Dragon – When taking acid, cold, fire, lightning or poison damage, you can use your reaction to gain resistance to that instance of damage a number of times equal to your proficiency bonus.
Gift of the Gem Dragon – When taking damage from a creature up to 10 feet from you they must take a strength saving throw or take 2d8 damage and be pushed 10 feet from you or on a passed save, half damage and not be pushed away.
Gift of the Metallic Dragon – Create spectral wings when you or an ally within 5 feet of you is hit by an attack to protect against that attack adding an extra AC equal to your proficiency bonus for that attack.
Mage Slayer – Make a melee attack against a creature that casts a spell within 5 feet of you.
Martial Adept – You can take the riposte maneuver which allows you to make an attack against a creature that attacks and misses you.
Orcish Fury – Immediately after using your relentless endurance trait, you can use your reaction to make one weapon attack.
Polearm Master – Can take an opportunity attack against a creature that enters your reach when wielding a polearm.
Second Chance – When hit by an attack, you can use your reaction to force that creature to reroll to hit. Can only be used once per combat.
Sentinel – Can take an opportunity attack even when a creature uses the disengage action. Hitting a creature with an opportunity attack causes their speed to become 0 for the rest of the turn. Can also make a reactionary attack against an enemy within 5 feet of you that attacks an ally.
Shield Master – If required to take a dexterity saving throw to take half damage against an effect, you can use your reaction to use your shield to take no damage if you succeed on your saving throw.
War Caster – If you could make an opportunity attack, you can instead cast a spell as a reaction at the creature as long as the spell targets only that creature and has a casting time of 1 action.
What are the best reactions?
This is a tricky question to answer as the answer can be highly situational and likely depends on your class and role in the party. However, some reactions are more useful than others.
Opportunity attacks are some of the most common reactions and are easily used by melee fighters making them very useful, especially if you combine conditions like fear to cause your enemies to attempt to run away.
Best reaction spells
Spells can be a very powerful option and essentially allow you a free spell use each turn meaning it’s a good idea to ensure your spell list has at least 1 or 2 reaction spells available.
Arguably one of the best of these is silvery barbs which can not only prevent an enemy’s attack or other d20 roll from succeeding, but also grants advantage to an ally’s next roll and is only a level 1 spell. Counterspell is almost universally useful against enemy spells and can stop something deadly like fireball automatically. Shield is also universally useful giving protection, especially to half-casters that might also find themselves in melee combat. Hellish rebuke is also one of the more powerful reactions, especially as it can deal substantial damage. It starts at 2d8 and increases by 1d8 every level at which you cast it.
Best reaction feats
Defensive duelist is very useful if you’re a dual wielder not benefitting from a shield giving you that extra AC. Fade away is very useful for gnomes, essentially getting you out of danger with invisibility. Polearm master is often considered one of the more powerful feats in the game as opportunity attacks whenever an enemy enters your range is very powerful, especially as you may not always have enemies leaving your range. This is particularly effective with a 10 foot range too. Combining polearm master with sentinel is also a really effective way to ensure you’re always getting attacks of opportunity against enemies, especially if you charge in headlong with some allies at your side.