How could you balance a Druid transforming into an owlbear and other monstrosities?

Question

The buzz around the new trailer for the Dungeons & Dragons movie includes much discussion of a scene in which the druid character transforms into an owlbear.

As far as I know there’s no RAW way for a druid to do this in fifth edition without access to the ninth-level spell shapechange, since an owlbear is a monstrosity, and Wild Shape and lower-level druid shapechanging spells all restrict the druid to transforming into beasts. (See also this question about the history of this ability.)

While allowing access to owlbear as a wild shape option at a level where they can access beast shapes of the same CR seems perfectly fine and balanced on its own, I’m interested in a broader allowance of fantastic creature options. This question makes clear the balance issues of just extending Wild Shape to access monstrosities as well as beasts, so I want to know: what is a simple, well-balanced option to allow a fifth edition druid to transform into at least some monstrosities, including an owlbear?

This might include some limitations similar to the usual Wild Shape restrictions on movement speeds (to rule out special powers like teleportation or petrification), a limited list of acceptable forms (which would need to include owlbears), and/or a specific cost or requirement, like a feat, a magic item or choice of a Druid Circle based on the idea. Ideally I would like this to be available at a relatively low level, perhaps 5 or 6, but a higher level restriction is fine if that’s appropriate for balance reasons.

There will be multiple possibilities; I would prefer the simplest, by which I mean the one with the fewest steps or choices for player and DM (i.e. a simple list of additional forms, or a single feat, spell or magic item, would be preferred over designing an entire subclass, but I’m open to any option if it is better).

As an example, I’ve found this homebrew “Monstrous Shapes” feat, but it feels like it might be a bit underpowered?

Answer 1

Adjust the Circle of the Moon Druid with DM guidance

The moon druid has a feature on level 10 called Elemental Wild Shape

At 10th level, you can expend two uses of Wild Shape at the same time to transform into an air elemental, an earth elemental, a fire elemental, or a water elemental.

The Elementals are all CR 5, and have interesting movement and other abilities (fast flying, moving through earth, setting things on fire etc.). In my experience, they have been used by our druid much more for those, than to just mash with them in combat.

You could agree on a list of four Monstrosities instead of Elementals for them, for Monstrous Wild Shape.

The total list of Monstrosities is very long, and includes a lot of weird stuff, so I think allowing any and trying to limit their abilities by exclusion would be unwieldy, and limiting by only including things like movement, vision, resistances and attacks would be a lot less fun -- then it is not really the creature. It would be very hard to claim this is balanced against the four elementals, if you allowed access to all, as you get access to a huge pool of unusual abilities.

Would limiting the CR help? Limiting the CR to top out at 3 would still allow you to pick many of the achetypcial creatures of D&D including Displacer Beasts, Rust Monsters, Carrion Crawlers, Mimics, and Owlbears.

Even with limiting the CR, I am not sure allowing to pick from all monstrosities is balanced unless you have a clause the DM can say "no" to ensure balance. For example, even CR 3 would include Basiliks, which give you unlimited, perpetual petrification (normally a sixth level spell, flesh to stone), Dopplegangers, which give you unlimited thought reading and excellent long duration impersonation, and Phase Spiders, which give you unlimited etherealness (normally a 7th level spell, etherealness).

If you limit it to purely "beast-like" monstrosities like the Owlbear that have no magical or supernatural special traits, resistances, damage or movement modes, then you also could just use the Circle of the Moon druids normal rules for beasts, and allow these. This would allow your druid to turn into an adult owlbear at level nine, as the rule for this (PHB p 69) is:

Starting at 6th level, you can transform into a beast with a challenge rating as high as your druid level divided by 3, rounded down.

So in the end, this would likely come down to a pre-made list of OK creatures, or to just working it out on a case by case basis with your DM.

Answer 2

No special traits/attacks other than those that beasts have

The wild shape rules already limit CR (which should factor in AC, HP, proficiency bonus, damage per round, and to some extent resistances and immunities) and the movement types of swimming and flying. Thus the real concern in allowing monstrosities is what 'Special Traits' a druid might have access to, as well as any 'fantastic' actions (such as attacks that cause petrification).

From the Monster Manual (p. 10):

Special Traits (which appear after a monster's challenge rating but before any actions or reactions) are characteristics that are likely to be relevant in a combat encounter and that require some explanation.

'Balance' is a complicated and contingent thing, and really needs to be evaluated on a case by case basis. A simple a priori principle would be to disallow any forms which grant traits or features not already granted by beast forms. For example, the titular Owlbear has Keen Sight and Keen Smell, but so do many of the beast forms already available to druids (and in fact, Keen Smell is the most common special trait). The Owlbear has no special traits or attack consequences that are not already possessed by beasts. Thus it is an acceptable monstrous wild shape, because it has no abilities that are not accessible to a druid with just beast shapes.

Applying this standard to the forms available in the Monster Manual should allow us to evaluate its usefulness:

Enhanced Offense

Trait	Beasts with this Trait	Monstrosities this would permit
Blood Frenzy (advantage on attacks)	Giant Shark, Hunter Shark, Quipper
Charge (extra damage and can knock prone)	Boar, Elk, Giant Boar, Giant Elk, Giant Goat, Giant Sea Horse, Goat, Rhinoceros	Centaur (along with ranged weapon attack), Peryton (along with three other traits and if we consider Dive Attack to be mechanically the same as Charge)
Pack Tactics (advantage on attacks)	Baboon, Blood Hawk, Dire Wolf, Giant Rat, Giant Vulture, Hyena, Jackal, Lion, Reef Shark, Vulture, Wolf
Poison (extra damage)	Giant Poisonous Snake, Giant Scorpion, Poisonous Snake, Scorpion
Poison (damage and may paralyze if target reaches 0hp)	Giant Centipede, Giant Spider, Giant Wasp, Giant Wolf Spider
Ranged Weapon Attack	Ape, Giant Ape	Centaur (along with Charge). Manticore (considering a druid is unlikely to complete a long rest in wild shape). Merrow (along with Amphibious)

Imposing conditions

Trait	Beasts with this Trait	Monstrosities this would permit
Disease	Giant Rat (variant)
Grapple	Tyranrosaurus Rex [sic], Giant Crab (two targets), Giant Scorpion (two targets), Octopus
Grapple and Restrain	Constrictor Snake, Crocodile, Giant Constrictor Snake, Giant Crocodile, Giant Octopus, Giant Toad
Knock Prone	Ankylosaurus, Dire Wolf, Giant Crocodile, Mastiff
Pounce (knock prone and bonus attack)	Allosaurus, Lion, Panther, Saber-Toothed Tiger, Tiger
Swallow	Giant Toad
Trampling Charge (knock prone and bonus attack)	Triceratops, Elephant, Mammoth, War Horse
Web	Giant Spider

Enhanced Defense and Escape

Trait	Beasts with this Trait	Monstrosities this would permit
Flyby	Pteranadon, Flying Snake, Giant Owl, Owl	Peryton (along with three other traits)
Ink Cloud	Giant Octopus, Octopus
Relentless	Boar, Giant Boar

Enhanced Senses

Trait	Beasts with this Trait	Monstrosities this would permit
Keen Hearing	Bat, Dire Wolf, Giant Bat, Giant Owl, Giant Weasel, Jackal, Killer Whale, Mastiff, Owl, Weasel, Wolf	Hook Horror. Worg (along with Keen Smell)
Keen Sight	Blood Hawk, Eagle, Giant Eagle, Giant Owl, Giant Vulture, Hawk, Owl, Vulture	Griffon and Hippogriff. Owlbear (along with Keen Smell). Peryton (along with three other traits)
Keen Smell	Badger, Black Bear, Brown Bear, Cat, Dire Wolf, Giant Badger, Giant Rat, Giant Vulture, Giant Weasel, Jackal, Lion, Mastiff, Panther, Polar Bear, Rat, Saber-Toothed Tiger, Tiger, Vulture, Weasel, Wolf	Owlbear (along with Keen Sight). Peryton (along with three other traits). Worg (along with Keen Hearing)
Web Sense	Giant Spider, Giant Wolf Spider, Spider

Special Breathing

Trait	Beasts with this Trait	Monstrosities this would permit
Amphibious	Crab, Frog, Giant Crab, Giant Frog, Giant Toad	Merrow (along with ranged weapon attack)
Hold Breath	Plesiosaurus, Crocodile, Giant Crocodile, Giant Lizard (variant), Giant Octopus (in air), Killer Whale, Octopus (in air)

Hiding

Trait	Beasts with this Trait	Monstrosities this would permit
Camouflage	Giant Octopus (underwater), Octopus (underwater)	Grick (stone), Alpha Grick (stone)

Special Movement

Trait	Beasts with this Trait	Monstrosities this would permit
Rampage	Giant Hyena
Running Leap	Lion
Spider Climb	Giant Lizard (variant), Giant Spider, Giant Wolf Spider, Spider
Standing Leap	Frog, Giant Frog, Giant Toad
Web Walker	Giant Spider, Giant Wolf Spider, Spider

Miscellaneous

Trait	Beasts with this Trait	Monstrosities this would permit
Beast of Burden	Mule
Illumination	Giant Fire Beetle
Mimicry	Raven
Sure-footed	Giant Goat, Goat, Mule

Restricting monstrous forms to those above that have beast-type abilities is a conservative approach, meaning it is more likely to unnecessarily restrict a monstrous form that would not be unbalanced than it is to permit one that that would. For example, by the time a druid is capable of a CR5 beast form, I don't think the bulette's 'deadly leap' would be unbalancing, and there are several others on the 'not allowed' list below that do not appear unbalanced compared to permitted beast shapes. However, as a first approximation, I think this approach has merit. It certainly can serve as a starting point for DMs considering the inclusion of monstrosities as wild shapes.

Monstrosities not allowed

Monstrosity not Allowed	Trait not present in any beast
Ankheg	Area of effect acid attack
Basilisk, Cockatrice, Gorgon, Medusa	Petrification
Behir	Lightning breath
Bulette	Deadly Leap
Darkmantle	False Appearance, Crush, Darkness Aura
Displacer Beast	Avoidance, Displacement
Doppelganger	Shapechanger, Ambusher, Surprise Attack, Read Thoughts
Ettercap	Its poison can cause the poisoned condition, unlike any beast
Hydra	Multiple Heads, Reactive Heads, Wakeful
Lamia	Innate Spellcasting, Intoxicating Touch
Mimic	Shapechanger, Adhesive, False Appearance
Minotaur	Labyrinthine Recall, Reckless
Spirit Naga, Guardian Naga	Spellcasting
Piercer	False Appearance
Young Rhemorhaz	Heated body
Roper	False Appearance, Reel
Rust Monster	Iron Scent, Rust Metal
Umber Hulk	Confusing Gaze, Tunneler
Yeti	Chilling Gaze
Abominable Yeti	Chilling Gaze, Cold Breath
Yuan-Ti Abomination, Yuan-Ti Malison	Shapechanger, Innate Spellcasting
Death Dog	Two-headed
Phase Spider	Ethereal Jaunt
Winter Wolf	Cold Breath

Answer 3

No ranged attacks, no magical effects

By and large, Beasts only have melee attacks and not much else. Generally, there is limited or no ability to attack at range, no fantastical movement, no special attacks (except some have poison).

If you observe the CR, fly and swim speed restrictions inherent in Wild Shape, and stick with these limits, you should be good.

Answer 4

Others have already provided what is probably the best answer - simply rule 0 it and apply DM discretion, ruling out particular monstrosities or limiting what abilities they have.

If your player just wants to be an owlbear and eat people, I recommend you accept one of those answers. However, if you actually want your player to be able to benefit from all the weird and fun abilities from all the monstrosities then...

Change wild shape from spontaneous, to prepared.

Wild shape is so amazingly useful because it provides the druid with a huge list of special abilities, and lets the druid choose, like a sorcerer, which to use at the time. This provides a huge amount of utility to a druid, as they can be capable of doing many things, without needing to commit any resources if the situational ability is not required.

If you allow a Druid to wild shape into any Beast or Monstrosity, that's equivalent to allowing a sorcerer a fivefold (estimate) increase in their spells known.

If one of your players asked if they could learn 5x as many spells as a sorcerer, you would tell them no, and that they should play a wizard isntead.

So if your druid wants 5x as many cool wild shape abilities, you should also require them to move from spontaneous to prepared.

Have them prepare a number of wild shapes at the start of each day. Potentially 1 per 2 druid levels.

It's also worth noting that the DM should still impose a soft gate on wild shape forms, even if they are doing this. In the wild shape ability, it must be a creature that the Druid has seen. This is a rule that DM's traditionally ignore - it's simply assumed that a druid has seen a wolf at some time in their backstory before the game started. But the same shouldn't apply for the druid having seen every single monstrosity. The druid should actually keep a list of wild shapes known - potentially starting with every beast at level 2, adding a couple of monstrosities that the druid would feasibly have seen in their backstory, and adding any monstrosity the party comes across.