A few weeks ago I gave my players a pop quiz about concentration. Researching the quiz taught me a lot about the rule, especially about how many things require it.
Q1. What specific things require concentration?
- Casting a spell that has duration "Concentration".
- Casting a spell with a casting time longer than a single Action or Reaction. This includes all ritual casting.
- Readying a spell.
- Using a feature. For example, Draconic Presence (Draconic Sorcerer lvl 18), Visions of the Past (Knowledge Cleric lvl 17), Invoke Duplicity (Trickery Cleric lvl 2), Dark Delerium (Archfey Warlock lvl 14), Minor Alchemy (Transmutation Wizard lvl 2). This might include the Paladin and Cleric Holy Water ritual and the Warlock pact Weapon ritual (the rules don't specify).
- Using a magic item. For example, marvellous pigments, ring of djinni summoning, ring of shooting stars.
Q2. What can break concentration? What is the roll and DC, if applicable?
- Doing something else that requires concentration (automatic).
- Entering Barbarian Rage (automatic).
- Taking damage (CON saving throw, DC is half the damage, minimum 10).
- Being incapacitated (automatic).
- Being killed (automatic).
- The environment around you (CON saving throw, DC varies).
