[RPG] Can the Conjure Animals spell summon swarms


The spell conjure animals (PHB, pg. 225) says:

You summon fey spirits that take the form of beasts and appear in unoccupied spaces that you can see within range. Choose one of the following options for what appears:

  • One beast of challenge rating 2 or lower

  • Two beasts of challenge rating 1 or lower

  • Four beasts of challenge rating 1/2 or lower

  • Eight beasts of challenge rating 1/4 or lower

Is it possible for conjure animals to summon a "swarm of X" creature, such as a swarm of rats or a swarm of insects?

On the one hand, I can see how the answer could be yes, simply because technically it is of type beast and is within the correct CR range, so RAW it should be possible to summon, say, four swarms of insects.

But on the other hand I can also see how the answer could be no, since it goes against the idea that you are summoning a specific number of beasts, and swarms are considered a "medium swarm of tiny creatures", meaning many creatures, many more than conjure animals says it can summon (i.e. the number of individual beasts in four swarms of insects is MANY more than "four beasts").

Which interpretation is correct (or is there a third interpretation)?

Note that D&DBeyond is not quite in sync with the books on this; in the description of the conjure animals spell, it lists example beasts, which include the swarms, but no such listing appears in the PHB's spell description, implying that these suggestions are the opinions of D&DBeyond's staff, not the designers (more likely it's just a listing of every monster of type "beast" for each CR).

Hence I would prefer for answers to be derived from the books rather than D&DBeyond where they differ. Also note that, although I mentioned the designers above, this is not a designer-reasons question; this is a RAW question. If there happens to be a Jeremy tweet clarifying this, great! But a RAW answer is what I'm looking for if such a tweet does not exist.

Best Answer

No; conjure animals summons a specified number of beasts of a certain CR, not a swarm of them

As written, the conjure animals spell summons a specified number of beasts, and a swarm is a collection of an indeterminate number of creatures. As the Monster Manual specifies (p. 337-339), each of the swarms listed there is a "Medium swarm of Tiny beasts"; a swarm is not a single "beast". The creatures within a swarm are not treated as distinct entities when treating the collective group as a swarm.

Thus, a swarm of any sort of animal would not qualify for any of the four options listed in the conjure animals spell.

Furthermore, the "The Nature of Swarms" sidebar in Appendix A (MM, p. 337) clarifies what swarms really represent:

The swarms presented here aren’t ordinary or benign assemblies of little creatures. They form as a result of some sinister or unwholesome influence. A vampire can summon swarms of bats and rats from the darkest corners of the night, while the very presence of a mummy lord can cause scarab beetles to boil up from the sand-filled depths of its tomb. A hag might have the power to turn swarms of ravens against her enemies, while a yuan-ti abomination might have swarms of poisonous snakes slithering in its wake. Even druids can’t charm these swarms, and their aggressiveness is borderline unnatural.

It's clear from the rules that swarms aren't designed to be treated like mundane animals, and that they don't simply congregate naturally or for benign reasons. Rather, they're a result of some malevolent influence, disturbing the natural order of things in some way.

The designers have been remarkably consistent in their interpretations of the rules regarding swarms: they are not a single beast.

As of October 2020, this question is explicitly addressed by an official ruling in the Sage Advice Compendium:

Can conjure animals summon a swarm?

No. Conjure animals summons individual creatures, and swarms are groups of creatures.

This official ruling is simple and straightforward, and matches the rules referenced above.

It also lines up with a number of unofficial rulings on Twitter about using Wild Shape to turn into a swarm - by Jeremy Crawford in January 2016 and again in November 2016, and by Chris Perkins in June 2015 - as well as an unofficial ruling on Twitter by Crawford in January 2015 about whether a swarm of quippers counts as one fish for the purpose of the trident of fish command (which can be used to cast dominate beast on "a beast that has an innate swimming speed").

As you can see, the rules themselves, the official ruling in the Sage Advice Compendium, and a number of unofficial rulings on Twitter all indicate that a swarm is not "one beast", but rather a collection of beasts.