There are a few options in 5e to delay casting. For example, the Ready action allows one to ready a spell:

When you ready a spell, you cast it as normal but hold its energy, which you release with your Reaction when the trigger occurs.

In this case, the casting takes place on the PC's turn, but the spell does not take effect until the reaction is triggered.

So, when does the duration of the spell actually begin? Obvious considerations are: 1) at the beginning of casting, 2) at the end of casting, 3) upon triggering.

Here is a pertinent example:

I want to cast Warding Bond, but I'm not wearing a ring. The spell stipulates that the caster and target must wear the rings for the duration of the spell. Can I cast the spell if I Ready an action to cast Warding Bond and set the trigger to “JZ puts a ring on it”, then JZ does just that?

The spell seems like it can only succeed if duration begins at the time of triggering, not at the time of casting.

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    \$\begingroup\$ Comments are not for extended discussion; this conversation trying to find context and edgecases has been moved to chat. \$\endgroup\$
    – Someone_Evil
    Sep 22, 2022 at 12:12

1 Answer 1


A spell's duration begins whenever the spell's effects begin

Here's how the rules define spell duration:

A spell's duration is the length of time the spell persists.

This length of time starts when the spell's effects start and ends when the spell's effects end (though other effects can cause the spell to end early, such as Dispel Magic or dropping concentration). There are a few exceptions to this, such as Levitate and Haste, which both explicitly specify effects that occur after the spell ends. However, the above is the general rule. (Additionally, as far as I know there are no spells that take effect before the casting is complete, with the exception of spells that explicitly or implicitly manipulate time.)

In most cases, a spell's effects (and thus its duration) begin immediately as soon as the casting is complete. One exception to this is a readied spell, as you have noted. In the case of a readied spell, the spell's effects do not begin until some time after the completion of the casting, when the specified trigger occurs and the caster uses their reaction to release the spell's energy. Thus, a readied spell's duration only begins when the spell's energy is released and the spell takes effect, not when the casting is completed.

Because readying a spell separates the casting and the start of the spell's duration, you'll need to carefully read the text of any game feature that interacts with spellcasting. For example, if an effect is triggered "when you cast a spell", in general that effect triggers on your turn when you use your action to cast the spell, even if you are readying the spell to release later. (Although note that if such a feature modifies the effects of the spell when it takes effect, the exact timing of when the effect occurs may turn out to be irrelevant after all.)

To take a specific example, Invisibility "ends for a target that attacks or casts a spell." In theory, you could ready a spell that doesn't involve an attack roll, then have someone cast Invisibility on you, and finally release the readied spell while invisible, and you would still be invisible after releasing it, because you never cast a spell while you were invisible.

One other weird edge case is that, if you ready a spell, it's possible to cast the spell but then never have its duration or effects begin. This can happen if the trigger never occurs before your next turn or if your concentration is broken before you release the spell.

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    \$\begingroup\$ I’m not sure if it’s worthwhile, but it may be interesting to add in the effects of concentration. And that to ready a spell will break the concentration of something else, but the duration of the new spell has not yet begun. \$\endgroup\$
    – NotArch
    Sep 21, 2022 at 22:55
  • \$\begingroup\$ @RyanCThompson , Cool! \$\endgroup\$
    – nonymous
    Sep 21, 2022 at 23:04
  • \$\begingroup\$ It would probably be good to address the specific example the OP brought up (though you already have my +1) \$\endgroup\$ Sep 22, 2022 at 11:12
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    \$\begingroup\$ @Exempt-Medic That example was added after I wrote my answer. And as I noted in another comment (now moved to chat), that particular example trips over a couple of edge cases that are outside the scope of this question. \$\endgroup\$ Sep 22, 2022 at 22:22
  • \$\begingroup\$ @RyanC.Thompson Ah, fair enough (I'll delete this comment shortly) \$\endgroup\$ Sep 22, 2022 at 22:25

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