Accordingly to the Rules Compendium:

The spell lasts for as long as you concentrate on it. Concentrating to maintain a spell is a standard action that doesn’t provoke attacks of opportunity.

Even though the rules for concentration were revised I still have one problem. I do not know exactly when does one start to concentrate on a spell. Does it start when one casts the spell?


3 Answers 3



Most spells start at the instant they are cast, and last as long as their duration. Concentration is simply a duration that lasts until you cancel it, but note:

Sometimes a spell lasts for a short time after you cease concentrating.

Concentration spells may be ended with no action:

A spell that depends on concentration is dismissible by its very nature, and dismissing it does not take an action, since all you have to do to end the spell is to stop concentrating on your turn.


Yes, on page 133 in the Rules Compendium, under CASTING TIME

You must continue concentration from the turn you start casting until the spell takes effect.

Different wording, but the same idea from the SRD, Combat, Actions in Combat, Cast a Spell

When you begin a spell that takes 1 round or longer to cast, you must continue the invocations, gestures, and concentration from one round to just before your turn in the next round (at least).


You only provoke attacks of opportunity when you begin casting a spell...


Yes, with a caveat

You start concentrating on a spell as soon as you cast it, which means that any effect that breaks concenytration can disrupt it since the moment of the casting.

Anyway, you need to start spending one round to keep concentrating from your next turn (i.e. you don't need to have a spare standard action this round in order to be able to keep your focus).

Apparently, the "concentrating to mantain a spell" is a kind of action you can take during your round and has nothing to do with the "concentration" that can be broken by effects, which can effectively be broken (if hit during casting with a properly readied action) even for spells that have a duration that is not "concentration".


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