What concentration is
Many of the most powerful spells in 5e, such as hold person, bless, haste, and hunter’s mark, require concentration. Concentration is the ongoing focus that keeps such a spell active for its listed duration. It is not an action and does not stop you from moving, attacking, or taking other actions. What it does stop is layering effects: you can hold exactly one concentration spell at a time.
Because of that one-at-a-time limit, casting a new concentration spell ends any concentration spell you already had running. This is true even if the new spell fizzles or its target succeeds on a save, so it is worth being sure before you swap.
The damage save
The rule that comes up most in play is losing concentration to damage. Whenever you take damage while concentrating, you must make a Constitution saving throw to keep the spell going. The DC is 10 or half the damage taken, whichever is higher.
| Damage taken | Concentration save DC |
|---|---|
| 1 to 20 | 10 |
| 21 to 22 | 11 |
| 40 | 20 |
| 50 | 25 |
If you take damage from more than one source at the same time, such as several attacks resolving together, make one separate save for each instance of damage, using that instance’s amount for the DC.
Other ways concentration ends
Damage is not the only threat. Concentration also ends if you become incapacitated, which includes being stunned, paralyzed, or knocked unconscious, and it ends immediately if you die. You can also choose to drop concentration at any time with no action required, which is handy when you want to free up focus for a new spell.
Boosting your odds
Some options make concentration far more reliable. A high Constitution modifier and proficiency in Constitution saves (from the Resilient feat or certain classes) raise the raw save. The War Caster feat grants advantage on every concentration saving throw made due to damage, which is one of the biggest reasons front-line casters take it.
How Adventure Codex handles it
Adventure Codex tracks the numbers that swing a concentration save, your current HP and the damage you just took, so the DC math is easy to read off at the table. When a big hit lands, you can see the damage total and settle the DC 10 or half-damage question instantly, then update the spellcaster’s state based on whether the save held.
Frequently asked questions
What is the concentration save DC in 5e?
It is 10 or half the damage you took, whichever is higher. So taking 22 damage means a DC 11 Constitution save, while any hit for 20 or less stays at the DC 10 minimum.
Can you concentrate on two spells at once?
No. You can only maintain concentration on one spell at a time. Casting another spell that requires concentration immediately ends the first one, even if the new spell fails.
What ends concentration besides damage?
Casting another concentration spell, being incapacitated (including stunned, paralyzed, or knocked unconscious), dying, or simply choosing to drop it. Some environmental effects can also force a check.