Blur 5e: Attack Disadvantage, Sight, and Concentration

Blur is the defensive illusion I consider when many attack rolls are more dangerous than one saving throw. It makes the caster visually difficult to strike for up to a minute, but the action to cast it, concentration requirement, and sight-based exceptions keep it from being universal protection.

Blur 5e — Quick Spell Reference

How Blur Works

For up to 1 minute, any creature has disadvantage on attack rolls against the caster. This applies to both weapon and spell attack rolls, including attacks from creatures that can otherwise see the caster clearly.

Blur affects melee and ranged attack rolls, but it does not change the caster’s Armor Class. An attacker still rolls against the normal AC, using disadvantage when the spell applies.

The 2014 spell has two exceptions. An attacker is unaffected if it does not rely on sight, such as a creature using blindsight, or if it can see through illusions, such as with truesight.

What Blur Does Not Do

Blur does not make the caster hidden, invisible, or lightly or heavily obscured. It does not provide advantage on Stealth checks, impose disadvantage on checks to detect the caster, add +2 to AC, or cause attacks to target an illusory duplicate. Mirror Image uses duplicates; Blur simply imposes disadvantage on qualifying attack rolls. Blink is another defensive alternative, but it works by moving the caster to the Ethereal Plane at uncertain times.

The spell also does not protect against effects that require saving throws rather than attack rolls. Fireball, Sacred Flame, and similar save-based effects work normally.

Blur does not prevent a creature from targeting the caster, and it does not make attacks miss automatically. It also provides no protection from damage or effects that occur without either an attack roll or a sight requirement.

Concentration and Timing

Blur requires concentration. Each time the caster takes damage, the caster may need to make a Constitution saving throw to maintain it. Casting another concentration spell also ends Blur.

Because Blur takes an action to cast, its defensive benefit must be weighed against using that action offensively. It is most valuable before a fight or when the expected reduction in successful attacks is worth the setup action and concentration.

The spell cannot be cast before initiative in every situation without consequence: verbal casting may be noticed, and the one-minute duration continues to pass outside combat.

Interactions

Disadvantage from Blur follows the normal advantage and disadvantage rules. Multiple sources of disadvantage do not stack, and one source of advantage cancels the disadvantage regardless of how many sources of either apply.

Blur can operate at the same time as Mirror Image because Mirror Image does not require concentration. Resolve whether an attack targets a duplicate under Mirror Image, then apply Blur’s disadvantage to an attack roll made against the caster, provided the attacker is not exempt from Blur.

If another effect grants advantage, the normal rule applies: any advantage and any disadvantage cancel, no matter how many sources of either exist. Blur therefore cannot force disadvantage when the attacker has advantage from another source.

Blur: 2014 vs. 2024 Rules

Blur’s level, casting time, duration, concentration, and basic disadvantage remain unchanged. The exception is worded more specifically in 2024: an attacker is immune when it perceives the caster with Blindsight or Truesight. The 2014 version more broadly exempts an attacker that does not rely on sight or can see through illusions. The quick-reference table and main rulings above use the 2014 wording.

FAQ

Does Blur increase Armor Class?

No. It imposes disadvantage on qualifying attack rolls against the caster.

Does Blur help with Stealth?

No. The spell provides no concealment or bonus to Stealth checks.

Does Blur work against saving-throw effects?

No. It affects attack rolls only.

Can blindsight or truesight bypass Blur?

Yes. An attacker that does not rely on sight or can see through illusions is unaffected.

Does Blur work against a grapple or shove?

It affects attack rolls. A 2014 grapple or shove uses a contested ability check rather than an attack roll, so Blur does not impose disadvantage on that check.