D&D Basic Rules, p77
Walls, trees, creatures, and other obstacles can provide cover during combat, making a target more difficult to harm. A target can benefit from cover only when an attack or other effect originates on the opposite side of the cover.
There are three degrees of cover. If a target is behind multiple sources of cover, only the most protective degree of cover applies; the degrees aren’t added together.
For example, if a target is behind a creature that gives half cover and a tree trunk that gives three-quarters cover, the target has three-quarters cover. A target with half cover has a +2 bonus to AC and Dexterity saving throws.
A target has half cover if an obstacle blocks at least half of its body. The obstacle might be a low wall, a large piece of furniture, a narrow tree trunk, or a creature, whether that creature is an enemy or a friend.
A target with three-quarters cover has a +5 bonus to AC and Dexterity saving throws. A target has three-quarters cover if about three-quarters of it is covered by an obstacle. The obstacle might be a portcullis, an arrow slit, or a thick tree trunk.
A target with total cover can’t be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.
How does cover work?
Cover in D&D is a mechanic whereby obscured creatures gain bonuses to their AC and dexterity saves, making them harder to hit.
There are three types of cover: half cover, three-quarters cover, and full cover.
A target has half cover if they’re behind cover which obscures over half of their body from an attacker. This gives a +2 bonus to the target’s AC and a +2 bonus to dexterity saves when resolving attacks from that attacker.
If three-quarters of a target’s body is obscured then they benefit from three-quarters cover. This works the same way as half cover except the target’s AC and dexterity save bonuses from cover are increased to +5.
A target has full cover if its body is fully obscured by its cover. If a target has full cover, it can’t be directly targeted by attacks or spells. The target can still be hit with AoE effects and some spells have special targeting parameters which allow them to be cast on targets the caster can’t see.
For example, the Dream spell can be cast on any creature that’s known by, and on the same plane of existence as, the caster.
Cover is uniquely determined between each attacker and target. A target could benefit from full cover against one attacker but have no cover against another.
Cover applies to all attack rolls but is most commonly relevant for attacks made with ranged weapons and spells. If two characters are within melee range of one another then usually there aren’t any obstacles between them unless they’re using Reach weapons like halberds or pikes.
How powerful is cover?
Cover is incredibly powerful! If a PC (Player Character) with a +6 modifier to hit attacks a goblin with 15 AC, the PC can expect to hit 60% of the time.
If the goblin is in three-quarters cover, the PC only has 35% chance to hit. This means, on average, that the number of successful attacks the PC makes is cut by almost half.
Three-quarters cover’s AC bonus of +5 is equivalent to the difference between wearing half plate and no armor at all.
The +2 AC bonus from half cover is also really significant, even if it appears less dramatic. Every extra point of AC has noticeable returns.
What can be used as cover?
Absolutely anything can be cover, so long as it would reasonably obstruct the patch from attacker to target. This includes objects and furnishings in the world and the terrain itself. A turn in a passageway, a low wall, or a cart in the street could all be cover.
Creatures can also be cover. This includes both the target’s allies and enemies. If your party’s tank is attacking an enemy at melee range, they may also be providing that enemy with cover against your party’s ranged attacks.
The Dungeon Master’s Guide also contains an optional rule for Hitting Cover, covered further down the page.
If your DM uses this rule, you should avoid attacking enemies who are gaining cover from your party members – you could risk friendly fire!
Even if you’re lucky and don’t hit your ally, your ally may still be upset that you put them at risk. You should instead reposition to flank and negate your target’s cover.
How does cover interact with other actions and conditions?
Cover and Prone
The Prone condition means that ranged attacks targeting you are made with disadvantage. This works in conjunction with cover – a prone target in three-quarters cover has a +5 bonus to AC and imposes disadvantage on the attack roll.
This combination will make your character extremely difficult to hit but it does come at a cost. Attackers within 5ft gain advantage instead of disadvantage. This means you’re very vulnerable if melee attackers can rush your position.
Cover and Hide
The Hide action requires your character to be outside of an enemy’s vision (see p177 in the Player’s Handbook).
This is determined by the same criteria as cover so being aware of cover in combat will also help you determine which spots you can use to Hide.
This is particularly important for rogues, who can hide as a bonus action to gain advantage from being an Unseen Attacker. This grants rogues extra damage through Sneak Attack.
Cover and A Readied Dash
In cases where an enemy is using your ally to gain cover against your party’s attacks, your ally can prepare a dash action for when you attack.
They can use this to drop prone and then stand up again after you’ve attacked. This prevents the target from benefitting from cover.
This has very niche usage but may sometimes be beneficial if you’re using high-damage ranged abilities in a confined space where you can’t easily reposition.
When to use cover:
- When you’re fighting against enemies with a lot of ranged attacks, and you can’t easily rush them.
- When you’re fighting in melee range, but there are also ranged enemies present.
- When you’re playing a ranged class, especially one with low survivability, like wizard and sorcerer.
Which characters benefit most from cover?
All characters gain huge benefits from cover but different characters utilize cover differently.
If you’re playing a melee character, it can be easy to assume that cover rules don’t apply to you. This is far from the truth.
You can benefit from huge benefits to your AC by positioning to obscure the line of sight for ranged attackers. You can carefully position a melee attacker between yourself and a ranged attacker or you can draw melee attackers to you, behind your cover.
You can also attack from behind cover, similarly to ranged players. This is particularly useful if you’re using a Reach weapon like a pike.
Ranged characters, and especially ranged spell casters, can gain huge benefits by attacking from cover. These characters can almost always position so they’re within cover but they sometimes need to choose between positioning in cover and positioning to negate enemy cover.
Spell-based classes like wizard and sorcerer have very low survivability and need every bit of it they can get. Martial ranged classes tend to have more survivability so they can often risk positioning more offensively and use cover where it’s convenient.
How To Bypass Cover
The Sharpshooter and Spell Sniper feats (both of which can be found on p170 of the Player’s Handbook) can be used by archers and spell casters respectively. These feats allow you to ignore half cover and three-quarters cover when making attack rolls.
Fighter’s Arcane Archer subclass can use Seeking Arrow (from p30 of Xanathar’s Guide to Everything). This ability allows you to fire an arrow that ignores all cover, including full cover.
There must be a path to the target that’s wide enough for the arrow to fit through and you must have seen the target within the last minute.
Certain spells and cantrips specify within their text that their target gains no benefit from cover. One example of this is the cleric cantrip Sacred Flame. AoE spells and spells that use saving throws besides dexterity are also not impacted by cover.
DM Tips For Cover
Bad Guys Taking Cover
There are a bunch of reasons why your bad guys should use cover.
It’s very easy for D&D combat to devolve into two sacks of HP standing still and rolling dice at each other until one falls over. Most DMs experience this when they’re starting out and it can be very offputting.
It’s boring for you, it’s boring for your players, and it can leave newer players and DMs feeling like D&D combat just isn’t for them.
The absolute easiest way to prevent these horrible, static encounters is to make sure, in every combat, that characters are constantly repositioning and interacting with the environment.
If your bad guys use cover them the environment immediately has meaning and positioning immediately becomes important. When the bad guys are thinking strategically and acting in a way that gives them clear benefits in a fight, players will immediately react to that.
Your players might reposition for a better angle of attack or they might rush the enemy’s position. In either case, combat becomes more mobile and more dynamic.
Your players will also probably start taking cover themselves and looking for opportunities to take cover in the environment, now that the possibility is in their minds.
As soon as some advantage is exploited against them, they’ll feel like they should be using it too. This is great! It means your players are viewing your world’s environments as real places which contain all kinds of everyday objects they can interact with.
Whether your bad guys use cover is also really useful in characterizing them. If an animal takes cover, that indicates that it’s thinking more strategically than your players might have assumed.
If human enemies choose not to use cover, maybe they’re reckless or fearless. What does it tell your players if a bad guy takes cover behind their own allies? Or if they stand in front, intentionally providing cover?
It’s particularly important, if slightly counterintuitive, to use cover against PCs with the Sharpshooter or Spell Sniper feats. Your bad guys may not be getting any benefit from cover but they probably don’t know that!
Plus, your player has sacrificed elsewhere so they can hit enemies who’re behind cover. It’d be unfair if they didn’t get the opportunity to do that.
The Hitting Cover rule
Page 272 of the Dungeon Master’s Guide has an optional rule for hitting cover. This primarily affects situations where characters are gaining cover from one another.
If an attack roll misses a creature that’s behind cover but it would have hit if the creature’s cover was absent, the attack has been blocked by the cover. If the initial attack roll also beats the AC of the cover, then the attack strikes the cover.
To give an example: a goblin with 15 AC is gaining three-quarters cover (and a +5 AC bonus) by standing behind a barbarian with 18 AC. A ranger with a +8 modifier to hit fires an arrow at the goblin and rolls 11.
In this case, the ranger’s total roll is 19. This would have beaten the goblin’s AC of 15 but doesn’t beat 20 AC once the cover bonus is considered. The roll of 19 beats the barbarian’s AC of 18, so the arrow hits the barbarian.
This rule is intended to encourage your players to attack and position in more realistic ways. Ranged characters should reposition to avoid any risk of hitting their allies.
The rule does allow for accidental friendly fire and many players won’t be familiar with it since it’s an optional rule.
To avoid drama at your table, you should let players know ahead of time that you plan to use this rule. You should also give them a warning, whenever they try to make an attack that could result in friendly fire, that they’re risking hitting an ally.
Ideally, your players would avoid putting their allies at risk. If a player repeatedly disregards their allies’ safety, then this can become disruptive. If this happens, it’s best addressed in a conversation outside of the game.