If a druid (multiclassed into sorcerer) casts Enlarge on himself so that he becomes a Large humanoid (approximately twelve feet tall), and he then Wild Shapes in a brown bear, is the brown bear form normal size or doubled in all dimensions?
The spell is still affecting the druid, and wild-shaping does not end effects on the wild-shaper, therefore the druid is still under the effects of the enlarge spell while wild-shaped.
At this point you might conclude that the question is settled: they would be an extra-large bear, because the spell is still working that that's what enlarge does. But that's not quite right.
Let us look at precisely what the enlarge spell's effect is, not what we might be tempted to mentally simplify it as (with all emphasis mine):
You cause a creature or an object you can see within range to grow larger or smaller for the duration.
Okay, so it doesn't make it 2× in every dimension as a static fact, it makes it grow at the beginning of the spell. That would mean it would not make any further changes afterwards, only sustain the initial change.
Well, maybe I'm reading too much into "to grow". Let's see what else it says it does:
The target's size doubles in all dimensions, and its weight is multiplied by eight. This growth increases its size by one category — from Medium to Large, for example. If there isn't enough room for the target to double its size, the creature or object attains the maximum possible size in the space available. Until the spell ends, the target also has advantage on Strength checks and Strength saving throws. The target's weapons also grow to match its new size. While these weapons are enlarged, the target's attacks with them deal 1d4 extra damage.
So it does look like it's a one-time growth, based on the verbs and nouns used. In particular, if enlarge is used on a target inside a smaller space than the maximum possible size, and then the target moves out of that space, they don't grow further once there is more room — the growth at the beginning of the spell is all you get, nothing more later.
So, the conclusion there is that the druid can shapechange into a form, and the enlarge effect is not applied to the new form. If they change into a sparrow or a bear, they get the normal statistics of a normal sparrow or normal bear.
That means that a druid that wants to dodge an inconvenient enlarge or reduce can easily do so by wild-shaping, but a druid that wants to benefit from enlarge or reduce in their wild-shaped form will have to somehow arrange for the spell to be cast after they wild-shape, so that it will grow their new form instead of just their previous form.
Approaching this from the opposite direction to @SevenSidedDie's answer.
You are an enlarged/reduced druid who chooses to use wild shape. Wild shape says:
Starting at 2nd level, you can use your action to magically assume the shape of a beast that you have seen before.
Your game statistics are replaced by the statistics of the beast, but you retain your alignment, personality, and Intelligence, Wisdom, and Charisma scores.
Transforming doesn’t break your concentration on a spell you’ve already cast ...
You retain the benefit of any features from your class, race, or other source and can use them if the new form is physically capable of doing so.
Looking at it this way raises a number of issues:
- Wild shape allows you to "assume the shape of a beast that you have seen before." When have you seen an enlarged/reduced brown bear?
- Is an enlarged/reduced brown bear in fact "the shape of a beast"?
- When I look at the statistics of a brown bear, one of them is its size. You assume that statistic.
- "Transforming doesn’t break your concentration" means that the enlarge/reduce spell is still in effect if you cast it, obviously, if someone else cast it then this is irrelevant. You then need to interpret the spell. @SevenSidedDie has argued that the growth/shrinkage happens at the start of the spell and then stops; if you agree with this position then the brown bear will remain the size given in its statistics. An equally valid (or better IMHO) interpretation is that the growth is ongoing but limited to a maximum/minimum size, this is why you need to keep concentrating; if you adopt this interpretation then the growth/shrinkage continues - you transform into a normal brown bear and then grow/shrink.
- "You retain the benefit of any features from ... other source" begs two questions
- Is being enlarged/reduced a feature? Probably.
- Does it provide a benefit? This is a non-trivial question because you may have been unwilling to be enlarged/reduced if the spell was cast on you with hostile intent. Personally the spell is of marginal usefulness when cast this way but I can see edge cases where there would be utility (Enlarging a pursuing ogre so it can't follow you down a narrow passage, reducing an enemy so they fall through a grate etc.).
My conclusion? Buggered if I know. This has so many twists and turns that the only sensible thing is for the DM to make a ruling. If it were me, I would allow it because:
- Its pretty cool.
- Its not overpowered, you have used a limited class feature and a spell and have to continue to concentrate to get the effect
- If you did it in the other order (wild shape then enlarge/reduce) you would get exactly the same effect - why should the order matter?
Just like other spell effects would remain active, Enlarge/Reduce will remain active. A druid cannot get rid of negative spell effects without making their save by wildshaping either; spells like Barkskin etc. will remain active too.
The argument "a druid hasn't seen an enlarged/reduced bear" makes no sense, because then the druid circles will take care to arrange a situation where they see a maximally buffed bear as part of their education. The description "grows into" is just a visual. It happens instantly, much like a fireball happens instantly and doesn't require an actual projectile roll or a round to be hurled and doesn't allow players to take cover behind the corner either - it just fills the area instantly.