Cover, Line of Sight, and Vision in D&D 5e

Cover is the rule that turns terrain into a tactical choice. Line of sight is the rule that decides whether you can target a creature with a spell. Vision rules decide whether you can see anything at all.

This guide covers all three, including the often-overlooked interaction between Dex saves and half cover.

Cover Types

Half Cover

+2 AC and Dex saves. The attacker can still see you, but part of you is obscured.

Examples: standing behind a low wall, half-hidden behind a friend, through a narrow opening.

Three-Quarters Cover

+5 AC and Dex saves. Most of you is obscured.

Examples: standing behind a large tree, peeking out from a corner.

Full Cover

You can't be targeted directly. The attacker needs to hit something else or destroy the cover.

Examples: behind a wall, around a corner with no line of sight.

Cover Stacks with Other Modifiers

Cover's AC bonus adds to your base AC. So a Plate + Shield character (AC 20) behind half cover has effective AC 22 for this attack.

Cover also affects Dex saves, which is huge for Fireballs and similar. +2 Dex save is roughly 10% fewer failures.

Line of Sight for Spells

Most spells require you to see the target (line of sight). Some spells specify "a point you can see," and this works through windows, doors, and other visual openings.

Spells that don't require sight: Fireball (requires a point; you need to see the point, not the targets in it), some AOE spells. Check each spell's text.

Line of effect: Separate from line of sight. Some spells need an unbroken path of energy. A wall of force blocks line of effect. Most walls block it.

Vision: Lightly vs. Heavily Obscured

Lightly Obscured

• You have disadvantage on Perception (sight) checks involving the lightly obscured area.

Examples: dim light, patchy fog, light foliage.

Heavily Obscured

• You are effectively blinded when trying to see creatures in the area.
• Your attacks against targets there have disadvantage.
• Their attacks against you have advantage (if they can see you).

Examples: darkness (without Darkvision), heavy fog, Darkness spell area.

Darkvision

Lets you see in dim light as if bright light and in darkness as if dim light.

• Dim light becomes bright: you see normally.
• Darkness becomes dim light: you can see, but colors are washed out, and everything is still lightly obscured (disadvantage on Perception).

Darkvision doesn't let you see in magical darkness (Darkness spell, some creatures' effects) unless you have Devil's Sight invocation or similar.

Magical Darkness

Darkness spell: 15-foot radius of magical darkness. Light-sources don't illuminate it. Only Devil's Sight, Sunburst, or True Seeing can see through it.

This is the Warlock Devil's Sight + Darkness combo. You see in it. Nobody else does. You have advantage on attacks; they have disadvantage.

Invisibility

Invisible creatures:

• Can't be seen without special senses (Truesight, See Invisibility spell).
• Attacks against them have disadvantage.
• Their attacks have advantage.

Invisibility breaks when you attack or cast a spell (unless Greater Invisibility, which doesn't break).

Terrain-Based Obscurement

• Fog (natural): Lightly obscured.
• Heavy fog: Heavily obscured.
• Smoke: Heavily obscured.
• Foliage: Varies. Bushes = lightly obscured. Dense forest = heavy cover possibly.

Ranged Attacks and Cover

A ranged attacker behind cover benefits from their cover. The target's cover (relative to the attacker) also applies.

If you're behind half cover and I'm behind half cover, attacks between us both get +2 AC on both sides. Cover stacks with itself this way.

In Combat

Cover is a common tactical consideration:

• Hide behind cover to attack, then break cover to attack again.
• Force enemies to expose themselves by moving them with pushes, shoves, or forced movement.
• Use terrain to your advantage. Walls, pillars, tables.

A cavalry Fighter with Polearm Master and reach has fewer cover issues because they can attack from 10 feet away. A short-reach melee fighter needs to move into position.

In Solo Play

Solo characters use cover heavily:

• Hide behind obstacles to set up Sneak Attack.
• Break line of sight to avoid spells that require sight.
• Position for cover before combat starts.

A solo Rogue with a crossbow and some walls in the environment is an extremely effective hit-and-fade build.

The Endlessness and Vision

Our AI Dungeon Master tracks cover, line of sight, lightly/heavily obscured conditions, and Darkvision. When you attack from behind half cover, the system applies the +2 AC for the attack. When you try to target a creature in magical darkness without Devil's Sight, the attack gets disadvantage.

For related reads, our combat rules guide, advantage and disadvantage guide, and opportunity attacks guide cover the broader combat system.

Final Takeaway

Cover and vision are spatial rules that reward thinking about the battlefield, not just the stat sheet. Pay attention to terrain. Break line of sight when spells threaten. Use cover aggressively.

Start a character on The Endlessness and feel terrain matter.