The recently released D&D Monsters by Type document from Wizards of the Coast points out some interesting potential wrinkles in the druid’s wild shape ability in the 5th edition of Dungeons & Dragons. Let’s take a look.
The description of wild shape says: “…you can use your action to assume the shape of a beast that you have seen before.” Note that “beast” is a specific creature type in D&D 5e. The druid’s level sets limits on the type of beast form assumed: A maximum challenge rating (CR) of 1/4 and no flying or swimming speed at 2nd level, max. CR of 1/2 and no flying speed at 4th level, and a max. CR of 1 and no movement limits at 8th level. The Circle of the Moon druid archetype increases the CR limits to druid level divided by 3 and rounded down (minimum of 1).
Given these guidelines and taking a look at the Beast table of D&D Monsters by Type, what do we note…?
Dinosaurs. Right off, the allosaurus, ankylosaurus, and other dinosaurs are on the table. Now, they’re CR 2 and 3, respectively, but a 6th or 9th level druid of the Circle of the Moon could turn into them. Sadly, turning into a T-rex would require a 24th level druid, but triceratops is available at 15th level, plesiosaurus at 6th level, and pteranodon at 8th level (because of the flying speed) – even a non-Circle of the Moon druid can turn into a pteranodon.
Giants. All of the various “giant” varieties of normal animals are on the beast list, meaning druids can wild shape into giant crabs, giant bats, or giant eagles, to name a few, so long as they qualify. Only a handful of giant animals are beyond the reach of non-Circle of the Moon druids, notably the giant scorpion and giant shark (cue the Jaws theme…).
Bugs. Likewise, a variety of insects and arachnids are also on the Beasts table, meaning druids can wild shape into giant centipedes and fire beetles, with higher levels opening up flying insects.
Climbing. While swim and fly speeds require higher level wild shape, beasts with a climb speed are fair game right from the get-go, so a druid can turn into a spider or a giant centipede to climb up walls or across ceilings.
Stealth. Similarly, there’s no size limit on wild shape so, while an ordinary mouse isn’t listed on the Beast table, a CR 0 rat is, so we can presume that a druid can also turn into a field mouse or other tiny creature for stealth purposes. In urban areas of most D&D worlds, stray dogs, cats, rats, and mice are so common as to go unnoticed, perfect camouflage. Presumably amoebas and bacteria are not classified as beasts, however, disappointing Disney’s version of Merlin from The Sword in the Stone. Still, a class variant of druid able to wild shape into diseases… (Eberron’s Children of Winter, anyone?)
Poison. Some of a druid’s potential wild shape forms are also poisonous: the giant centipede can do 3d6 poison damage, and the scorpion 1d8 poison damage, with the spider doing 1d4 poison damage. At 4th level, various snake forms become available as well.
Swarms. One of the most intriguing implications of the Beasts table is that it (and the Monster Manual) list various swarms as “beasts,” meaning—according to the wild shape description as written—it should be possible for a druid of sufficient level to turn into a swarm of rats, ravens, or flying insects! An 8th level druid can do the cool fantasy movie trope of turning into a flock of ravens and flying away, while a 6th level druid of the Circle of the Moon can turn into a swarm of poisonous snakes!
Variety. Even without some of the cool stuff above, there are a lot of options.
A 2nd level druid can wild shape into a(n): axe beak, boar, camel, draft horse, elk, giant badger, giant centipede, giant fire beetle, giant lizard, giant rat, giant weasel, giant wolf spider, mastiff, mule, panther, pony, rat, riding horse, scorpion, spider, swarm of rats, or a wolf.
A 4th level druid can wild shape into all of the above as well as a(n): ape, black bear, constrictor snake, crocodile, giant crab, giant frog, giant goat, giant poisonous snake, giant sea horse, giant wasp, poisonous snake, reef shark, rhinoceros, or warhorse.
Obviously, one of the primary controls on wild shape, other than the mechanical limits on forms, is the clause “that you have seen before.” If there’s no way the druid character has seen a pteranodon before, for example (because all of the dinosaurs in the setting live on an isolated island the druid hasn’t visited), then that shape isn’t available. Seeking out and studying some exotic beasts in order to learn their forms might even be a goal for a druid adventurer. Still, even within its limits, there’s a lot of hidden potential in the wild shape ability for players of druid characters to explore!
Steve Kenson 
My daughter’s 5th Level Druid is going to wreak some hella good badness with these tips. Thank you!
Worth noting that you can’t turn into a swarm. Swarm is a type, “Swarm of Tiny beasts.” You can turn into a single beast, so you can turn into a component of a swarm, but not an entire swarm.
Interesting. I think the plurality of “beasts” is more significant, since “swarm” is not listed as a creature type (under “Type” in the Monster Manual). Since wild shape says “a beast” and swarms are listed as beasts (plural), they could be considered off-limits. Of course, even if they are off-limits, the ability to turn into swarms would be an interesting ability for a druid sub-class.
game designer says no
Hmmmm … pity.
For druids rules as written seems to be an entirely different thing. Natural Armour is not Armour if your druid multiclasses into Barbarian or Monk.
Theres also the arguement of what creatures you have seen before. The question lies. Before what? Before becoming a druid or from the point of being able to learn how to wildshape.
Swarm not a beast. In the monster manual its written under beasts. Also sacrificing the cool movie troupe of changing into a swarm of bats or locusts.
I’d also play on the idea that, although Chris Perkins says no, Chris Perkins isn’t running your game, or even going to play or notice your game.
It was Mike Mearls who wrote on the first page of the PHB
“Above all else, D&D is yours. The friendships you make around the table will be unique to you. The adventures you embark on. the characters you create, the memories you make-these will be yours. D&D is your personal corner of the universe, a place where you have free reign to do as you wish. Go forth now. Read the rules of the game and the story of its worlds, but always remember that you are the one who brings them to life. They are nothing without the spark of life that you give them.”
If you own the Sword Coast Adventurer’s Guide then this extract from page 18 will shed more light on that players and game masters are encouraged to create their own story.
“The world today seems a place filled with new lands and opportunities, where those who dare can leave their mark. Students of history and those elves and dwarves who recall the past that short-lived humans see as distant perceive a world much like it was over a century ago. For most folk, wild tales of people empowered by the gods, and of far-off lands returned to the world, are the subjects of fireside chatter. Daily concerns and the dangers and opportunities just beyond their doors take precedence, and plenty of both remain on the Sword Coast and in the North.”
Swarm… My character is a Drow Druid, so more probable she has seen a swarm of insects or rats, possibly a swarm of snakes, than a polar bear. She’s also chosen circle of the moon and wondering what CR2 creatures she can shift to.
I think it is DM’s discretion on whether to allow a swarm. Pedantic argument to say ‘swarm’ as plural of beast means it disqualifies a Druid from shifting in to that beast/s.
Let’s go one step further, in the opposite direction, if a lawyer’s pedantic argument is the game. One of the limitations of Wildshape, is that the Druid cannot use the Legendary or Lair abilities of the ‘creature’ shifted into (PHB p67). Something must have been within contemplation, to make a requirement where there is no ,beast’ in the Monster Manual which has a Legendary or Lair ability. What was in contemplation? I would argue that ‘beast’ is not intended as a specific category, but beast-like ‘creature’ is the appropriate interpretation. If not, ‘beast’ would continue to be used in reference to Legendary and Lair abilities. ‘Creature’ is used. So, the entire Monster Manual is open for Wildshape for beast-like ‘creatures’.
This includes Dragons. In the past, the Druid has been able to shift in to a dragon, subject to size limitations. CR rating has replaced the size limiting mechanic. So, a character which has seen a dragon should be able to shift in to that dragon, subject to CR limitations (instead of the v3.5 size limitation).
So, my Druid (circle if the moon) has seen a green dragon and thinks she can shift in to a Green Dragon Wyrmling when she gets to level 6 (CR2).
Why can’t she?
(I want a more sophisticated argument than ‘the Monster Manual doesn’t identify it as a beast’. I think I have made out that the PHB has a confused vision of ‘beast’ and ‘creature’ for the purpose of Wildshape).
The definition of a beast from the dictionary is “An animal, especially a large or dangerous four-footed one.”
And yet some would argue a dragon is not an animal. It sure is large and dangerous with four feet. And is also seem to act a lot like that of a cat and looks like a reptile.
If I was a DM in a homebrew game it would be a matter of balancing the table with the other players. If the other players had items or benefits which made them just as cool and you could scale the encounter rating up fairly then I would say go for it. But if you were an experienced player with relatively new or players who used weak characters then I’d discuss that with the player and ask yeah perhaps between the lines you can transform into a dragon but can you help me out as a DM and not break the game for the others.
Its 2 cents.
I beg to differ… 4 footed?!? An Ape is an animal and it does have 4 feet. A fish? Bug?
Humans are animals… 😉 but Dnd wants creatures without souls that are animal.
Beasts have raw intelligence, Eagle being the smartest, and no languages.
Dragons have language, smarts and claws that manipulate. Therefore can’t wildshape Into humans, dragons etc
I was always under the impression that with a swarm, you become the ‘hive mind’ of the swarm and only if there is enough creatures presents.
Example: Your druid is in an urban area attempting an escape. he finds that there is a bunch of rats scatter around but they are not unified. He turns into a rat and with his own stats being possibly superior to the other rats, manages to coerce them into forming a swarm of rats with him being the swarm’s mind.
I could be wrong however, but this is just my thoughts on how a Druid interacts with a swarm when Wild Shaping. I mostly go with a Giant Toad monster, eat my poor enemy, digest them, and move on. Or take on the form of an angry Bear or Dire Wolf/Tiger and maul the poor enemy to shreds. Ahhh and the Giant Spider or Centipede… always love the ideas of climbing the ceiling and getting the drop on my foes if the DM allows it.
For swarms I would have them give up something else like make it a homebrew feat for example and take it instead of an ability increase.
i have found a loophole in the “you have seen” wording. With a researcher ability, acquired by the sage background. Researcher gives you the ability to “recall any information or where it is located”. So, technically, you have seen all the monsters and presumably the Monster Manual.
So bam, you can be a dinosaur.
That’s some pretty thin justification, even by my loose standards. Still, Wizards offered additional guidelines on learning wild shapes in Unearthed Arcana recently, and Jeremy Crawford clarified that swarms are out, as I recall. Still, as folks continue to mention, it’s your game to do with as you like.
Is there any limitations on conjure animals? Can’t I conjure a dino and then study it, and then wild shape into it? Doesn’t seem too hard to work that out.
I didn’t see it in your writing…
But it should be noted that a druid at 5th level can start summoning CR2 and lower creatures with conjure Animal. Contention on whether you can choose the animal…
My own argument is that ‘you choose X of type’…
With these spells you can summon creatures long dead to your world. Like dinosaurs.
One addendum to your lists… Stirge is a beast… so is a Single Rot Grub… since you can’t be a disease… you can be an assassin.
Could you study dinosaur bones at a museum to be able to turn into a dinosaur? I’m looking at a campaign that seems to have some fleshed out city locals and wondered if taxadermied and fossilized skeletons would fit the bill.
Hmmm … I wouldn’t think so, personally, but that’s heavily up to the GM. I would tend towards “has seen a living example” as the minimum requirement for wild shape, but that could vary a lot based on the campaign.