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 an 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) with out 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.

  • \$\begingroup\$ The headline of your answer might be misleading. The original question was "Can a concentration spell be cast without actually concentrating on it for an “instant” effect?". And I think the right answer here would be "Yes you could, but it would not held you". I did not post my own answer as you already cited the rule in question correctly. \$\endgroup\$ – Tobias Kremer Jan 9 '18 at 16:07
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    \$\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
  • \$\begingroup\$ I know we are splitting hairs here, but: The Players Handbook says " You can end concentration at any time (no action required)." So you can end your concentration the very instant you finish casting so effectively never actually concentrating on it. (So the amount of time you spend concentrating is actually zero.) \$\endgroup\$ – Tobias Kremer Jan 10 '18 at 21:09
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    \$\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

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.


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