D&D 5e Concentration Rules: RAW vs RAI and Every Edge Case
D&D 5e concentration rules exist to prevent spellcasters from stacking multiple powerful ongoing effects simultaneously. The mechanic is simple in principle — you can only concentrate on one spell at a time, and taking damage forces a saving throw to maintain it. In practice, concentration generates more table arguments than almost any other mechanic in 5e. The rules have gaps, the RAI is often inferred rather than stated, and several common interactions produce answers that surprise even experienced players.
This post covers the full RAW, the DC math, and every meaningful edge case — including Arcane Ward, Wild Shape, Polymorph, and Temp HP interactions.
How Concentration Works: The RAW Foundation
Concentration ends under four conditions:
- Casting another concentration spell — immediately, no save
- Taking damage — requires a Constitution saving throw
- Becoming incapacitated — immediately, no save
- Dying or dropping to 0 HP — immediately, no save
The DM may also call for a DC 10 Constitution saving throw in response to environmental phenomena — a crashing wave, an earthquake, severe weather. This is explicitly DM discretion, not a mandatory rule.
You can end concentration voluntarily at any time with no action required.
The Concentration Save DC
When you take damage while concentrating, the DC is:
DC = 10 or half the damage taken (rounded down), whichever is higher
| Damage Taken | Concentration DC |
|---|---|
| 1–20 | 10 |
| 21 | 10 (half = 10, rounds down to 10) |
| 22 | 11 |
| 30 | 15 |
| 40 | 20 |
| 50 | 25 |
The DC only exceeds 10 when damage reaches 22 or higher. A goblin hitting you for 4 damage is a flat DC 10 save every time. This is important: most damage in early combat is DC 10, which means your Constitution modifier and proficiency (if applicable) determine whether concentration is a genuine threat or a minor tax.
Multiple sources of damage in the same instance require separate saves. If an arrow hits you for 8 damage and a fire trap deals 12 damage simultaneously, you roll two saves — one at DC 10, one at DC 10. Each is resolved independently.
The Math: How Hard Is It to Lose Concentration?
The Constitution saving throw uses your CON modifier. Most classes are not proficient in Constitution saves, which means your survival rate depends heavily on two factors: your CON score and whether you’ve invested in concentration protection.
| CON Score | CON Modifier | Base DC 10 Success Rate | With Proficiency (+2) |
|---|---|---|---|
| 10 | +0 | 55% | 65% |
| 14 | +2 | 65% | 75% |
| 16 | +3 | 70% | 80% |
| 20 | +5 | 80% | 90% |
War Caster feat grants advantage on concentration saves, which on a DC 10 save turns a 65% success rate into roughly 88%. It’s the single most impactful concentration protection in the game.
Resilient (Constitution) grants proficiency in Constitution saves. At higher levels when proficiency bonus reaches +5 or +6, it mathematically overtakes War Caster on raw numbers — but War Caster also provides other benefits (somatic components with hands full, opportunity attack spellcasting) that make it better at lower levels.
Both stacked — advantage and proficiency — makes concentration extremely difficult to break on standard damage values.
Arcane Ward and Concentration: The Damage Redirect Question
The Abjuration Wizard’s Arcane Ward reads: “Whenever you take damage, the ward takes it instead. If the ward is reduced to 0 hit points, you take any remaining damage.”
The question: if the Ward absorbs all of the incoming damage, do you make a concentration save?
RAW answer: The concentration check triggers when you take damage. If the Ward absorbs all damage and you take 0, the trigger condition — taking damage — never applies to you. No concentration save is required.
This is the correct RAW reading and the most widely supported ruling at tables and in community consensus. The Ward is absorbing damage on your behalf; you personally took zero damage; the save never fires.
The partial damage case: If an attack deals more damage than the Ward has HP remaining, the excess carries through to you. In that case, you did take damage — only the amount that exceeded the Ward. Your concentration save DC is based on the damage you took, not the total incoming damage.
Example: A fireball deals 28 damage. Your Ward has 10 HP remaining. The Ward absorbs 10, you take 18. Concentration DC = 10 (half of 18 is 9, which is lower than 10). You roll at DC 10, not DC 14.
This is a meaningful advantage — the Ward not only reduces damage but also reduces the DC of the save you’re forced to make.
RAI consideration: Nothing in the text suggests the designers intended Arcane Ward to fully negate concentration checks, but nothing contradicts it either. The RAW is clean here. This ruling stands.
Temporary Hit Points and Concentration: A Common Misconception
A widespread table ruling holds that temporary hit points (Temp HP) absorb damage before it reaches you, and therefore — like Arcane Ward — they should negate concentration checks when they absorb the full hit.
This is incorrect RAW.
Temporary hit points explicitly state they are a buffer against damage, but the PHB rules on concentration do not carve out an exception for temp HP. The concentration save triggers when you take damage. Temp HP reduce the damage you take but do not eliminate the trigger — you still took damage, just less of it.
The practical result: if you have 5 Temp HP and take 8 damage, you take 3 real damage, but you still make a concentration save at DC 10 (half of 3 is 1, which is below 10, so DC stays at 10).
This is the key distinction between Temp HP and Arcane Ward. The Ward says the ward takes the damage instead of you — a true redirect. Temp HP reduce damage that still hits you. Two different mechanics producing two different concentration outcomes.
Wild Shape and Concentration: The Beast CON Question
A Druid can cast a concentration spell, then use Wild Shape to transform. Concentration is not broken by transforming — Wild Shape does not cause damage, does not cast a spell, and does not incapacitate the Druid. The previously cast concentration spell continues.
However, while in Wild Shape form, the Druid uses the beast’s physical statistics, including its Constitution score. This matters because concentration saves use your current CON modifier.
RAW: Wild Shape replaces your physical ability scores (STR, DEX, CON) with the beast’s. When you make a Constitution saving throw while in Wild Shape, you use the beast’s CON modifier.
This has a significant practical implication for Moon Druids who cast concentration spells before transforming. A Brown Bear has CON 16 (+3). A Dire Wolf has CON 15 (+2). Many useful beast forms have reasonable Constitution scores, meaning Wild Shape can actually improve your concentration saves if you were playing a low-CON Druid.
Conversely, picking a beast form with CON 10 as a strategy for any other reason may undermine your concentration spell. Check the stat block before you transform.
Proficiency note: You retain your class proficiencies in Wild Shape, including saving throw proficiencies. If you have War Caster or Resilient (CON), those still apply. You use the beast’s CON modifier but your own proficiency bonus if applicable.
Polymorph and Concentration: Two Separate Questions
Polymorph creates two distinct concentration issues that often get conflated.
Question 1: Can a Polymorphed Creature Maintain Concentration?
Polymorph specifies that the target’s “game statistics, including mental ability scores, are replaced by the statistics of the beast.” This raises the question of whether a polymorphed caster — say, a Wizard who casts Polymorph on themselves — can maintain concentration on a previously cast spell.
RAW answer: The spell states the target’s statistics are replaced. However, concentration is not a statistic — it’s a spellcasting feature. The question is whether the text “game statistics are replaced” includes the capacity to concentrate.
The dominant RAW reading is that Polymorph breaks the capacity to maintain concentration spells when cast on a caster, because the beast form has no spellcasting and concentration is intrinsically tied to spellcasting ability. This contrasts with Wild Shape, which explicitly preserves class features. Polymorph has no such language.
This is one of the most actively debated rulings in 5e. Many DMs allow concentration to persist through self-Polymorph. The RAI appears to lean toward Polymorph breaking concentration for the target, but no official ruling has fully closed the debate.
Question 2: Does Polymorph Require Concentration If Cast on an Enemy?
Yes. Polymorph has the Concentration tag. If you Polymorph an enemy into a sheep and then take damage, you make a concentration save or the enemy reverts. This is RAW and unambiguous.
Other Edge Cases Worth Knowing
Casting a non-concentration spell while concentrating is fine. Concentration only breaks if you cast another spell that also requires concentration. Casting Fireball while concentrating on Bless does not break Bless.
Spell-like abilities and concentration. Some class features that require concentration are not spells. The Barbarian’s Rage in 2024 does not end concentration. A Paladin’s concentration-based Aura features interact with damage the same way spells do. Check each feature individually.
Incapacitated immediately ends concentration — no save. Stunned, paralyzed, unconscious, or otherwise incapacitated ends concentration the moment the condition applies. A Monk’s Stunning Strike landing on a concentrating caster is a hard counter.
Dropping to 0 HP ends concentration. No matter how high your CON modifier is, hitting 0 HP drops your spell. This is sometimes forgotten when a caster is stabilized by another character — the concentration spell is already gone.
Environmental saves are DC 10. Any DM-called concentration save from environmental phenomena defaults to DC 10. This is a soft floor — rough seas, earthquakes, and similar hazards are no more threatening to concentration than a grazing hit.
Concentration and bonus action spells. Casting a spell as a bonus action while concentrating is fine as long as the bonus action spell is not itself a concentration spell. The bonus action spell rule (you can only cast a cantrip with your action if you’ve cast a bonus action spell) is separate from the concentration rule.
Protecting Concentration: Priority Order
If you’re playing a concentration-dependent caster, here’s the investment hierarchy:
1. War Caster (feat) — advantage on concentration saves plus somatic casting in melee. Best early investment.
2. Constitution score — CON 16+ as a baseline. Every +1 to CON is +1 to every concentration save you’ll ever make.
3. Resilient (Constitution) — proficiency in CON saves. Scales with level. Overtakes War Caster in raw math at high Proficiency Bonus values.
4. Positioning — not a feat, but avoiding damage entirely is better than saving against it. Back row placement, cover, and range matter.
5. Shield spell — costs a reaction and a spell slot but can prevent the hit that forces the save in the first place.
Bottom Line
The D&D 5e concentration rules are cleaner than they appear, but several interactions — Arcane Ward, Temp HP, Wild Shape, and Polymorph — expose gaps between RAW and common table assumptions. The most important distinctions: Arcane Ward genuinely redirects damage and can negate concentration saves when it absorbs the full hit, while Temp HP merely reduces damage and still triggers the save. Wild Shape replaces your CON modifier but preserves your proficiency and feats. Polymorph’s interaction with the caster’s concentration capacity remains contested. Know the difference between these cases and you’ll spend less time arguing mid-combat and more time playing.