The book says:

Concentration. Some spells require you to maintain concentration in order to keep their magic active. If you lose concentration, such a spell ends.

So what happens if, for example, you are already concentrating on a spell, and cast Witch Bolt without concentrating. Would you get the initial arc of blue energy, or would it not even go off?

I am asking if you can cast a spell that says concentration without concentrating for an immediate effect. This would be useful to avoid interrupting your existing concentration. In essence, if you are concentrating on thing A (doesn't have to be a spell since other things need concentration), can you cast a concentration spell getting an immediate effect without losing concentration on thing A?

Since the definition of concentration is to keep the spell active (meaning it is already active) I would think that you would get the initial effect (if it had one) without the need to concentrate on it.


No. Casting a concentration spell immediately breaks any existing concentration.

One of the rules clarifications in Xanathar's Guide to Everything (pg. 5) addresses this issue directly:

As soon as you start casting a spell or using a special ability that requires concentration, your concentration on another effect ends instantly.

  • 1
    \$\begingroup\$ @TobiasKremer I disagree--you cannot cast a concentration spell without actually concentrating on it, which is what the headline question asks. \$\endgroup\$
    – Icyfire
    Jan 9 '18 at 16:26
  • 6
    \$\begingroup\$ @TobiasKremer While that's technically true, it still interrupts your pre-existing concentration, which is the main point of the question. \$\endgroup\$
    – Icyfire
    Jan 10 '18 at 21:24
  • \$\begingroup\$ This question is also now explicitly addressed in the latest Sage Advice Compendium: "If I’m concentrating on a spell and I cast another spell that requires concentration, when does my concentration on the first spell end? If you’re concentrating on a spell, your concentration on it ends immediately when you start casting another spell that requires concentration." You may want to update your answer accordingly \$\endgroup\$ Oct 9 '20 at 15:29

A concentration spell requires concentration all the time

You concentrate on a concentration spell from the instant you start to cast it until you stop concentrating. As such any previous concentration spell loses concentration at that instant.

  • \$\begingroup\$ But why? This answer could be improved by citing the relevant rules. \$\endgroup\$ Mar 30 at 17:32

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