D&D 5e Concentration: The Complete Guide

You cast Bless on your party. The fighter is hitting more. The rogue is landing sneak attacks. Everything is going great. Then a goblin plinks you with an arrow for 4 damage and suddenly you need to make a Constitution saving throw or the whole thing collapses.

Welcome to concentration, the mechanic that turns spellcasters into high-priority targets and makes Constitution the secret best stat for anyone who slings spells.

This guide covers everything: the rules as written, the math behind concentration checks, tactical advice for maintaining your spells, and a list of the best concentration spells worth protecting.

What Is Concentration?

Concentration is a spellcasting mechanic that limits how many powerful ongoing effects you can maintain at once. If a spell has a duration that says "Concentration, up to X minutes/hours," it requires your active mental focus to keep running.

The core rule is simple: you can only concentrate on one spell at a time.

Cast Bless and then try to cast Spirit Guardians? Bless drops immediately, before the new spell even takes effect. You do not get to choose. The moment you begin concentrating on a new spell, the old one ends. No overlap. No stacking.

This single rule shapes the entire spellcasting system. Without it, high-level casters would just layer buff after buff until the party was basically invincible. Concentration is the leash that keeps magic balanced.

What Requires Concentration?

Any spell with "Concentration" in its duration line. You will see it written as:

Duration: Concentration, up to 1 minute

or similar. If the duration just says "1 minute" (without the concentration tag), it does not require concentration and will persist regardless of what else you do.

Quick way to remember: most spells that create ongoing effects (buffs, debuffs, summons, area control) require concentration. Most spells that do something instantly (damage, healing, teleportation) do not.

You can look up which of your spells need concentration in any full spell list. Knowing this before combat starts is not optional. It is homework, and it saves lives.

What Breaks Concentration?

Four things can end your concentration:

1. Taking Damage (Concentration Check)

Whenever you take damage while concentrating on a spell, you must make a Constitution saving throw to maintain concentration. This is the most common way concentration breaks, and the DC is:

DC = 10 or half the damage taken, whichever is higher.

So if you take 15 damage, the DC is 15 (half of 15, rounded down, is 7, but 10 is higher... wait, half of 15 is 7.5, which rounds down to 7. The DC is 10). If you take 24 damage, the DC is 12 (half of 24). If you take 40 damage, the DC is 20.

The minimum DC is always 10, which means even chip damage forces a meaningful check. That 1 damage from stepping on a caltrop? DC 10 Constitution save. That ancient dragon's breath weapon for 72 damage? DC 36. Good luck.

Important: if you take damage from multiple sources simultaneously (like multiple missiles from Magic Missile), you make a separate concentration check for each source of damage. Three missiles hitting you means three DC 10 checks, not one check against the total. This is one of the reasons Magic Missile is secretly a fantastic concentration-breaker.

2. Casting Another Concentration Spell

As mentioned above, starting concentration on a new spell immediately ends the old one. You do not get to "switch" at will either. Once the old spell drops, if the new spell fails (target makes their save, for instance), you have lost both. Risky business.

3. Being Incapacitated or Killed

If you become incapacitated (stunned, paralyzed, unconscious, etc.) or die, concentration ends immediately. This makes death saves even more consequential for spellcasters, because dropping to 0 HP not only puts you in mortal danger but also nukes whatever spell you were maintaining.

Getting stunned by a Mind Flayer's Mind Blast is particularly devastating for this reason. You lose your concentration AND you cannot act on your turn. Double whammy.

4. Voluntary Ending

You can choose to end concentration at any time, no action required. This rarely comes up, but it matters when your Hypnotic Pattern is about to wear off and you want to cast Wall of Force in the same turn. Drop the old spell, cast the new one. Clean transition.

The Math: How Hard Are Concentration Checks?

The probabilities matter here, because they determine whether your +2 Constitution modifier is "fine" or "a liability."

For a DC 10 Constitution save:

| Con Save Bonus | Success Rate | |---|---| | +0 | 55% | | +2 | 65% | | +4 | 75% | | +6 | 85% | | +8 | 95% | | +10+ | Auto-success |

At +0, you are basically flipping a coin every time you take damage. At +4 (16 Constitution, no proficiency), you are passing three-quarters of the time. Solid, but you will still fail one in four checks, and in a long fight with multiple sources of damage, that adds up fast.

This is why Constitution is so important for spellcasters and why the War Caster feat and Resilient (Constitution) are considered near-mandatory for certain builds.

Key Features and Feats for Concentration

War Caster (Feat)

Gives you advantage on Constitution saving throws to maintain concentration. This roughly turns a 65% success rate into an 88% success rate, or a 75% rate into a 94% rate. It is one of the best feats in the game for any caster who plans to be anywhere near combat.

Resilient: Constitution (Feat)

Gives you proficiency in Constitution saving throws. At lower levels, this is slightly worse than War Caster. At higher levels (when your proficiency bonus is +5 or +6), it overtakes War Caster in raw numbers. Many optimizers take both eventually.

Paladin's Aura of Protection

Adds your Charisma modifier to all saving throws for you and allies within 10 feet. A Paladin with 20 Charisma gives everyone nearby a +5 to concentration checks. Absurdly good.

Bladesinger's Extra Attack Feature

Not directly related to concentration, but Bladesingers add their Intelligence modifier to Constitution saves for concentration, making them surprisingly tough to interrupt.

Eldritch Mind (Warlock Invocation)

Advantage on concentration checks, just like War Caster but without the other benefits. If you are a Warlock who only wants concentration protection, this is a free pickup.

Popular Concentration Spells Worth Protecting

Not all concentration spells are created equal. Here are the ones you really do not want to drop:

Tier 1: Lose This and Cry

• Bless (1st level): +1d4 to attack rolls and saving throws for three allies. Simple, powerful, scales with your entire party's action output.
• Spirit Guardians (3rd level): 3d8 radiant/necrotic damage to enemies that enter or start their turn in a 15-foot radius around you. The Cleric's signature "walk into a room and everything dies" spell.
• Hypnotic Pattern (3rd level): Incapacitate every creature in a 30-foot cube that fails a Wisdom save. Encounter-ending.
• Polymorph (4th level): Turn the fighter into a Giant Ape with 157 HP. Or turn the enemy dragon into a turtle. Losing this at the wrong moment is catastrophic.
• Wall of Force (5th level): An indestructible wall that splits encounters in half. If this drops early, your tactical plan collapses.
• Conjure Animals (3rd level): Eight wolves. Just... eight wolves. The action economy alone is worth protecting (see our action economy guide for why this matters so much).

Tier 2: Annoying to Lose, But You Will Survive

• Hex/Hunter's Mark (1st level): Extra damage on attacks. Solid, but losing it is not the end of the world.
• Hold Person (2nd level): Paralyze a humanoid. Devastating when it works, but it only affects one target and they get a save every turn anyway.
• Faerie Fire (1st level): Advantage on attacks against affected creatures. Great for the party, but not as back-breaking to lose as the Tier 1 spells.
• Haste (3rd level): Incredible buff, but losing concentration on Haste causes the target to lose their next turn entirely. This is the "high risk, high reward" concentration spell. Losing it is actively punishing, not just disappointing.

Tier 3: Nice While It Lasted

• Detect Magic (1st level): Useful out of combat, rarely something you are maintaining under fire.
• Fly (3rd level): Important to maintain if your ally is 60 feet in the air. Less critical if they are 5 feet up. Context-dependent.
• Greater Invisibility (4th level): Advantage on attacks and disadvantage on attacks against you. Excellent, but losing it just returns you to normal instead of causing something terrible.

Tactical Tips for Maintaining Concentration

1. Stay Out of Damage Range

The best concentration check is one you never have to make. Stay behind cover. Stay behind the fighter. Stay at maximum spell range. If you are a squishy Wizard standing in melee range, you are asking to lose your spell.

2. Use Cover and Positioning

Half cover (+2 to AC and Dexterity saves) and three-quarters cover (+5) make you harder to hit in the first place. A well-placed pillar between you and the enemy archers can save your concentration more reliably than any feat.

3. Stack Your Constitution

Between a decent Constitution score, proficiency (Resilient), advantage (War Caster), and features like the Paladin's aura, you can make concentration checks nearly automatic. Prioritize this if your character's game plan revolves around a key concentration spell.

4. Choose Wisely Before Combat

Look at your concentration spells and pick one before initiative is rolled. Trying to decide between Bless and Spirit Guardians while the DM is asking for your first action is a recipe for indecision and regret. Know your default pick.

5. Do Not Stack Concentration on One Character

If your Cleric is concentrating on Spirit Guardians and your Wizard is concentrating on Hypnotic Pattern, losing one is survivable. If both casters are relying on the same buff (Bless + Bless from two different casters), you are doubling up resources inefficiently. Spread your concentration around.

Concentration in Solo Play

When you are playing solo with a single character, concentration management gets both simpler and more stressful. Simpler because you only have one concentration slot to track. More stressful because there is no backup caster to maintain a second spell.

The Endlessness AI tracks your concentration automatically, applies the correct DCs when you take damage, and will prompt you for the saving throw. It also handles concentration for any NPC allies traveling with you, which means you can coordinate concentration effects between your character and your companions just like in a group game.

If you are building a solo character and plan to lean on concentration spells, War Caster should be very high on your feat priority list. Check out our features to see how the AI handles all of this automatically.

Common Mistakes

"I am concentrating on two spells at once." You cannot. Ever. One concentration spell, maximum. If you cast a second one, the first ends immediately.

"I failed the concentration check but I want to use my reaction to reroll." Unless you have a specific feature that allows this (like a Chronurgy Wizard's Chronal Shift), you cannot. The check is final.

"I took 20 damage from a fireball, so the DC is 20." The DC is half the damage taken (10) or 10, whichever is higher. Half of 20 is 10, and 10 equals 10, so the DC is 10. The DC only exceeds 10 when you take more than 20 damage.

"I lost concentration, so the spell slot is refunded." Absolutely not. The slot is spent. The spell was cast. Concentration breaking just ends the effect early. This is why losing concentration on a 5th-level spell slot feels so bad.

"The enemy hit me twice, so I make one concentration check against the total damage." Each hit is a separate check. Two hits of 8 damage means two DC 10 checks, not one DC 10 check. More hits means more chances to fail, which is why multi-attack enemies are so dangerous to casters.

Quick Reference

| Trigger | What Happens | |---|---| | Take damage | Con save (DC 10 or half damage, higher) | | Cast another concentration spell | Previous spell ends immediately | | Become incapacitated | Concentration ends | | Die | Concentration ends (obviously) | | Choose to end | Ends immediately, no action needed | | Multiple damage sources | Separate check for each source |

Wrapping Up

Concentration is the invisible backbone of 5e spellcasting. It prevents casters from stacking buffs into oblivion, creates meaningful tactical decisions about which spell to maintain, and makes Constitution a relevant stat for every character who casts spells.

Master the rules, invest in your Constitution save, position carefully, and choose your concentration spell wisely before the fight starts. Do those four things and you will get dramatically more value out of your spell slots.

And if you do lose concentration on Spirit Guardians in round one? Hey, at least you learned something. Probably about standing behind the Paladin next time.