Assume you cast Delayed Blast Fireball, another creature then casts Dispel Magic on it. Would you be able to end your concentration--causing it to explode--as it is being dispelled? If so, do you do it before or after the other creature rolls their check, assuming they did not upcast Dispel Magic?

Delayed Blast Fireball:

A beam of yellow light flashes from your pointing finger, then condenses to linger at a chosen point within range as a glowing bead for the duration. When the spell ends, either because your concentration is broken or because you decide to end it, the bead blossoms with a low roar into an explosion of flame that spreads around corners.

Dispel Magic:

Choose one creature, object, or magical effect within range. Any spell of 3rd level or lower on the target ends. For each spell of 4th level or higher on the target, make an ability check using your spellcasting ability. The DC equals 10 + the spell’s level. On a successful check, the spell ends.


1 Answer 1


It will depend on your DM

The concentration rules say

You can end concentration at any time (no action required).

So you do not need a reaction or anything, you can drop concentration at any time. That includes, when someone tries to cast dispel magic on your bead.

Now, one question is if you know the caster is casting dispel magic. Many DMs and optional rules in Xanathar's Guide to Everything require require an reaction for that. Once the spell ist cast successfully, it is probably too late and your bead will be dispelled, as reactions normally only resovle after their trigger finishes. So if you do not just want to blindly explode your bead because someone is starting to cast a spell, you'd need a table rule that allows you to identify spells as they are cast, before they are cast.

Even if you just blindly want to let go of concentration, as dispel magic is a single action, instantaneous spell, it is not entirely clear from the rules what of these two things that the both of you try to do at the same time would happen first. The timing resolution of D&D is that formal or granular.

What happens first if two things happen simultaneously is not exactly defined by the game. So, by default that is up to the DM and by another optional rule in Xanathar's by the active player. If that rule is used, and your DM rules that dropping and casting happen at the same time, then if the opponent casts dispel magic on their own turn, they can put it first and resolve it and your bead is dispelled. If they do it as a Reaction on yours, you can put dropping concentration first, and have it go off.

  • \$\begingroup\$ Not my downvote, but I think this should be the other way around. In principle no, but it depends on your DM. My DM lets us, and I would do too, but rules wise this is an almost certain no. \$\endgroup\$
    – SeriousBri
    Commented Oct 13, 2023 at 8:55
  • 2
    \$\begingroup\$ This one is a pretty straightforward duplicate, and you made it really easy to find the dupe target by linking it in your answer. \$\endgroup\$ Commented Oct 13, 2023 at 8:56
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    \$\begingroup\$ @ThomasMarkov I didn't think so because if you can drop anytime is not the whole answer really, but I also have no time right now to review further, so fine to have it closed for now. \$\endgroup\$ Commented Oct 13, 2023 at 10:55

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