Some spells, like true polymorph, has language that says (emphasis mine)

If you concentrate on this spell for the full duration, the spell lasts until it is dispelled.

This seems to suggest that the duration is over and the spell simply lasts until dispelled. If you are looking at the rules around Combining Spell Effects, does "lasts until dispelled" count as a duration? Or is it outside of that mechanic and the spell actually has no ongoing 'duration'?


3 Answers 3



Player's Handbook, p.203, "Duration":

A spell's duration is the length of time the spell persists. A duration can be expressed in rounds, minutes, hours, or even years. Some spells specify that their effects last until the spells are dispelled or destroyed.

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    \$\begingroup\$ That still creates a minor paradox in true polymorph: After concentrating for the "full duration", the duration extends. Technically, it should say that from that point on, concentration is no longer required. \$\endgroup\$ Commented Dec 10, 2019 at 18:44
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    \$\begingroup\$ @NautArch No need to feel silly, "Until Dispelled" is pretty obtuse. Something like "Indefinitely Until Dispelled" would be a lot clearer. \$\endgroup\$ Commented Dec 10, 2019 at 19:04
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    \$\begingroup\$ @MarsPlastic not really, True Polymorph has two different durations - if you concentrate for the full duration of the first, you get the second. \$\endgroup\$
    – Dale M
    Commented Dec 10, 2019 at 20:22
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    \$\begingroup\$ So, just to make this extremely clear; if I polymorph someone into a sheep, and then focus on that for the entire duration, they're now just a sheep until someone casts a dispel effect on them for some reason, without me having to do anything extra, right? \$\endgroup\$ Commented Dec 11, 2019 at 9:00
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    \$\begingroup\$ @JohnHamilton: Yes. \$\endgroup\$ Commented Dec 11, 2019 at 11:40

I think there is a misunderstanding here (also inhowfar the question is asked). That's not your fault though, the wording of the spell description is pretty bad.

It says that the duration is for as long as you concentrate (up to 1 hour). It also says that if you concentrate for the full duration, then the spell lasts until it is dispelled (which arguably means the "duration" extends, so you need to keep concentrating or else it will not last until dispelled!).

Now, what the text meant to say, obviously, is that it lasts for as long as you concentrate, and if that is less than an hour, the effect ceases to exist.
But if you concentrate for the full hour, then the effect becomes quasi-permanent (without further concentrating). Until dispelled.
Otherwise, it doesn't make any sense at all.

Is "until dispelled" a duration now, or is it not? I beg to differ with Quadratic Wizard's point of view. Although the quoted paragraph does start with "A spell's duration is...", it doesn't say that "until dispelled" counts as duration at all.
It speaks of rounds, minutes, hours, or years as duration. And then, it states that some spells last until dispelled (i.e. have no such duration).


No, lasts until dispelled is not a duration

The duration of a spell is explicitly given in the spell text:

Duration: Concentration, Up to 1 hour

The effects of a spell can last longer, as stated in the rules - in this case potentially until dispelled, but the spell itself is no longer active, only the effects of it. For example, the hit points cured by cure wounds persist until destroyed, but that doesn’t mean that the cure wounds spell’s “instantaneous” duration is extended until that happens. The effects linger, but the spell that created the effect has ended.

Spells only do what they say they do. In this case, the spell says its duration is up to an hour, and its effects can last until dispelled. The spell text does not say its duration is extended indefinitely if you concentrate for an hour, so it is not.

For the purposes of combining spell effects

The second casting of True Polymorph will suppress the first casting. If that spell is dropped before an hour passes, the target will revert to the form it took from the first True Polymorph. If the second casting is concentrated on for a full hour, the from it took from the second casting will persist as well, suppressing the effect of the first until it is dispelled.

  • \$\begingroup\$ To the downvoters - please let me know what you find unsatisfactory about my answer, or where you consider the error in my rules-reading is \$\endgroup\$
    – Ty Hayes
    Commented Dec 13, 2019 at 12:23
  • \$\begingroup\$ I didn't downvote, but I can guess why they may have happened. There are conflicting definitions of what a spell duration is. (see PHB 203) as an example, a spell's duration is the length of time a spell persists. Your definitions of a spell effect (the spells effect as long as it is there) compared to spell (the spells up to when it 'lasts until dispelled') doesn't exactly break this, but people thought it conflicts too much. \$\endgroup\$
    – Dezvul
    Commented Dec 15, 2019 at 7:17
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    \$\begingroup\$ I would bring this up though, it does conflict with your definitions, dispel reads: "Any spell of 3rd level or lower... ends. For each spell of 4th level or higher... make an ability check... on a successful check the spell ends. Dispel magic only dispels spells, not spell effects. If something 'lasts until dispelled' it could only be a spell. Thus the spell is still persisting, which means by "duration's" definition, the spell's duration has not ended. \$\endgroup\$
    – Dezvul
    Commented Dec 15, 2019 at 7:19
  • \$\begingroup\$ here's 10 points. \$\endgroup\$
    – Dezvul
    Commented Dec 15, 2019 at 7:23
  • \$\begingroup\$ @Dezvul Thanks for the feedback (and the upvote, I assume). I see the potential issue with Dispel Magic, although I would argue that the "until dispelled" mentioned in the True Polymorph description is an exception that allows a no-longer active spell to be dispelled rather than an indication that it is still active. \$\endgroup\$
    – Ty Hayes
    Commented Dec 15, 2019 at 13:30

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