DnD Cover Rules in Combat

Cover rules in Dungeons & Dragons 5th Edition define how physical obstructions between a combatant and an attacker modify attack rolls and Dexterity saving throws. The mechanic sits within the broader combat rules framework and is activated whenever a creature's line of sight to a target is partially or fully obstructed by terrain, structures, or other creatures. Correct application of cover determines the difference between a successful hit and a deflected shot — making it one of the most spatially consequential rulings a Dungeon Master makes during tactical combat.

Definition and Scope

Cover is a positional condition applied to a creature when another object, structure, or creature occupies the space between that target and an attacker's point of origin. The Player's Handbook and the D&D Basic Rules identify three discrete cover states: half cover, three-quarters cover, and total cover. Each state is mutually exclusive — a creature benefits from only the highest applicable tier when obstruction sources overlap.

Cover is not a status condition in the same sense as those catalogued in the D&D Conditions Reference; it is a spatial relationship that must be actively assessed at the moment of each attack or saving throw. Cover benefits do not persist automatically — movement that changes the geometry between attacker and target can eliminate cover mid-turn.

The rules distinguish cover from concealment (handled under light and vision rules) and from stealth (stealth and hiding rules). A creature can be concealed without having cover, and vice versa.

How It Works

Cover modifies 2 specific game mechanics:

1. Attack rolls targeting a creature with cover are penalized by a bonus applied to the target's Armor Class.
2. Dexterity saving throws made by a creature with cover gain a bonus when the source of the effect originates from a direction the cover faces.

The 3 cover tiers operate as follows:

1. Half Cover (+2 bonus) — The target is obscured by roughly half its body. Qualifying obstructions include low walls, large furniture, a narrow tree trunk, or another creature standing between attacker and target. The target gains +2 to AC and Dexterity saving throws.

2. Three-Quarters Cover (+5 bonus) — Approximately three-quarters of the target's body is obstructed. Qualifying obstructions include arrow slits, a sturdy portcullis, a thick tree, or a dense cluster of creatures. The target gains +5 to AC and Dexterity saving throws.

3. Total Cover (cannot be targeted directly) — The target is completely concealed behind an obstruction. A creature with total cover cannot be the target of an attack or spell that requires a clear line of effect, per the D&D Basic Rules. Area-of-effect spells that do not require targeting a creature specifically can still reach creatures in total cover if the effect's area extends to their space.

The Dungeon Master adjudicates cover by determining whether a straight line drawn from the attacker's space to any corner of the target's space passes through or along an obstruction. If that line is blocked for more than half the target's exposed area, the higher tier applies.

This geometric assessment connects directly to movement and positioning rules, since a creature's grid position determines which obstruction angles apply.

Common Scenarios

Low stone wall on an outdoor battlefield — A fighter firing a crossbow over a 3-foot wall at an enemy crouching behind it assigns half cover (+2 to AC) to the enemy. If the enemy is additionally behind a second barrier obscuring three-quarters of their body, the +5 bonus supersedes the +2.

Arrow slits in a fortification — A guard firing through an arrow slit benefits from three-quarters cover (+5 to AC and Dex saves) because the slit exposes only a narrow portion of the guard's body. Attackers outside the wall cannot easily target the guard directly; only attacks aimed specifically through the slit's angle maintain a valid line of effect.

A creature using another creature as cover — A Goblin standing directly behind an Ogre can gain half cover if the Ogre's body obstructs roughly half the Goblin's profile from the attacker's perspective. This situation frequently arises in grappling scenarios where a held creature is positioned as a living shield.

Area-of-effect spells and total cover — A wizard casting Fireball can place the spell's point of origin beyond a wall, reaching creatures in total cover if the 20-foot radius extends to their space. Total cover does not protect against area effects that do not require line of effect to the target — a distinction the D&D spellcasting rules govern by differentiating "targeting a creature" from "affecting an area."

Invisible attackers — Cover bonuses still apply against attacks from invisible attackers. The advantage and disadvantage rules govern the attack roll itself, but any applicable cover bonus to AC remains active regardless of the attacker's visibility.

Decision Boundaries

The Dungeon Master's adjudication of cover hinges on 4 recurring boundary conditions:

1. Overlapping cover sources — When a target is behind both a low wall (+2) and a creature (+2), only the highest applicable tier (+2) applies, not a cumulative +4. Cover bonuses do not stack.

2. Partial obstruction at grid edges — On a 5-foot grid, a creature whose space touches the edge of an obstruction may or may not qualify for cover depending on whether the line from attacker to target corners clears or clips the obstacle. The Dungeon Master makes this call; the D&D Basic Rules recommend the corner-to-corner geometric method as the default.

3. Cover versus the attacker's elevation — A creature firing from a tower or elevated position may have a line of effect that bypasses ground-level obstructions entirely, removing cover that would otherwise apply. Elevation changes require reassessing cover geometry at each attack. This intersects with environmental hazards rules in outdoor terrain scenarios.

4. Half cover versus three-quarters cover comparison — The practical difference between +2 and +5 is significant: a +5 bonus to AC means an attacker who would normally hit on a roll of 12 or higher now needs a 17 or higher — shifting hit probability by roughly 25 percentage points. That gap makes the correct classification of obstruction type a tactically material decision, not a cosmetic one.

For Dungeon Masters building encounters where cover is a primary tactical variable, the encounter building rules address how terrain complexity interacts with encounter difficulty. The full conceptual structure of how combat resolution works — including the relationship between cover, attack rolls, and saving throws — is outlined in the how DnD works conceptual overview. The dndrules.com index provides access to the complete ruleset reference across all combat and exploration mechanics.

References

• D&D Basic Rules — Wizards of the Coast / D&D Beyond (Free Official Reference)
• D&D Beyond Rules Glossary — Cover
• Dungeon Master's Guide — Wizards of the Coast (Official Print Reference)
• D&D Adventurers League — Organized Play Documentation