The Circle of Spores druid's Halo of Spores feature (Guildmasters' Guide to Ravnica, p. 27) states the following:

When a creature you can see moves into a space within 10 feet of you or starts its turn there, you can use your reaction to deal 1d4 necrotic damage to that creature unless it succeeds on a Constitution saving throw against your spell save DC.

(Emphasis mine)

My initial understanding was that this translates to: First your reaction is used (and thus "consumed"), then the creature would roll the Con save. Hence, if the creature succeeded, the reaction would have been wasted with no result.

However, upon second inspection I realise that it could also translate to this: You first declare you would like to use the feature, then the creature makes the save, and only if it fails is the reaction consumed to deal damage.

I'd be grateful for any help on this. Which approach is correct here? Is your reaction used regardless of whether the other creature succeeds on the saving throw?

Thanks in advance!

  • \$\begingroup\$ Rule books other than the player's handbook aren't always as carefully worded to avoid rule loopholes like this. It should be obvious how they meant to write it, as the answers explain. \$\endgroup\$ Feb 22, 2019 at 2:46

2 Answers 2


The first option - if the target makes a save, your reaction has already been used.

I agree that the sentence by itself is ambiguous. However, from my experience, any feature in 5e that forces a save and requires some kind of action consumes the action regardless of the result of the save. Therefore, I believe the same thing is intended here.

Notably, there are some features that you can choose to use after you know if you succeed, but afaik they all depend on you hitting with an attack.

Regardless, think of the Halo of Spores in-universe: you're using your reaction to blast the opponent with your spores, therefore your reaction is used regardless of the save. You don't ask your opponent "Hey, would you like to get blasted with spores? Yes? Well, here you go!", using your reaction only if he agrees/fails to defy you ;)

  • 2
    \$\begingroup\$ Good answer. Suggestion: "...but afaik they all depend on you hitting with an attack" and the text usually explains that they are exceptional in that way. So, since it doesn't say your reaction isn't wasted if they succeed on the save, there's no reason to suspect it is. \$\endgroup\$ Feb 21, 2019 at 21:23

The reaction is used.

According to the simplest reading of the text, you use your reaction to cause the effect. The foe then takes damage unless it saves. This is consistent with the other rules. In general, there is no ability that grants a reaction that is returned to you if a condition subsequent is not met. In the absence of specific wording to the contrary, we must assume this follows the general rules.


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