The Shapechanger trait is not affected by antimagic field
The Sage Advice Compendium tells us how to determine whether a feature is magical (p. 17, "Is the breath weapon of a dragon magical?"):
Determining whether a game feature is magical is straightforward. Ask yourself these questions about the feature:
Is it a magic item?
Is it a spell? ...
Sure, You're the DM.
If you want there to be a Curse that has entrapped a Dragon in Human Form, then you can invent one. There is no need for RAW to support this--creating curses-as-plot-devices is entirely within your purview as the DM.
However, there are some things to consider...similar things have come up in games I've designed when adding in extra ...
It means "don't use a different stat block".
"Statistics" is a game term defined in MM p 6-11:
A monster’s statistics, sometimes referred to as its stat block, provide the essential information that you need to run the monster.
So in fact the sentence you've highlighted is telling you not to use the stats of another monster like the Giant Poisonous ...
Based on the comments, the problem is 100% not how quick the Druid's shapeshifting is, it's that you haven't been making GM moves on 6−.
Restricting the move is not at all the answer. The GM doesn't have that authority in the first place, and more importantly, the Shapeshifter move needs GM moves on its misses in order for it to function correctly. If you ...
Up to the DM
There are no official creature weights in 5e, just size categories. Specific heights and weights are up to the DM to narrate to fit the story.
This DM would say it weighs what a normal bat weighs :)
But if you want to go with heavy bat, by all means do so! If that fits your story and vision, there is nothing wrong with it. And mechanically it ...
Different creatures, different abilities, different rules
While all of these fall under shape-changing, each creature/ability/spell has its own set of rules.
This is a great example of specific over general with regard to the ruleset. Shape-changing is a general rule allowing a creature to change their form, while each instances of Shapechange/Polymorph has ...
It is hard to argue that it would expel the druid
Issue 1: total cover
The meld into stone spell does not explicitly say that you gain total cover in the stone, but it implies it heavily. You cannot see the outside, but can move around inside (you can provide somatic components). There is mention of what happens if the stone is harmed, but no mention of the ...
As you say, shapeshifting a lot is reasonable. It's a thing the Druid can do and there are no (overt…) restrictions on the move, so adding some is a bad idea and will just take away what makes the Druid the Druid.
But it does have restrictions; they're just not obvious because the move is carefully taking advantage of restrictions that are baked into the ...
No, the druid does not revert.
A shapechanger makes its saving throw with disadvantage. If it fails, it also instantly reverts to its original form and can't assume a different form until it leaves the spell's light.
As this is a new paragraph separate from the first paragraph of the spell description, and the paragraph exists to describe the specifics ...
You couldn't change into a lich because a lich isn't humanoid or a beast
The change shape feature of the Brass dragon says (emphasis mine):
The dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own.
A lich is an undead, not a humanoid or beast. So a brass dragon cannot change shape into a lich. For a ...
According to (the archived version of) a 2013 article from the Wizards' website:
In addition to their shapechanging, doppelgangers have the ability to
read thoughts. In the short term, a doppelganger can read thoughts to
aid it when tricking people around it. When impersonating a specific
victim, a doppelganger likes to spend an hour or so every day
RAW, it seems you quoted the relevant part of the rule already.
Destroy Water. You destroy up to 10 gallons of water in an open
container within range. Alternatively, you destroy fog in a 30-foot
cube within range.
The serpent form is not water in an open container or fog, and again RAW, should not be subject to damage from the spell. Spells don't ...
For the purposes of being affected by effects, it depends on the creature
Depending on the creature, the shapeshifting ability usually describes which statistics are kept and which are not. For more details on what counts as statistics you can see this question. The statistics are what determines what a creature counts as.
For example, the werewolf states ...
I'd use Occam's razor to say he weighs the same as a normal bat. The reasoning for this goes:
He can masquerade convincingly as a normal bat. That's attractive to me as a DM for plot purposes. It means he doesn't stand out in a crowd of bats, and can follow and spy on the characters easily and naturally.
This means he needs to be able to land on things that ...
The specific text of the metallic dragons' Change Shape action always includes, emphasis mine:
The dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies.
In a new form, the dragon retains its alignment, hit points, Hit Dice, ability ...
Use silver and truth
You say that the devils have made some sort of safe zone, but they are secretly dealing with the Lamia on the side. However, they, being devils and well versed in the idea of binding clauses, don't truly trust her, and why should they? Lamias are chaotic evil, they can't be expected to uphold their end of the contract.
So instead of just ...
Case 1, the Oni remains with 34HP.
As you quoted in Shapechange:
Other than its size, its statistics are the same in each form.
So all things in the Oni's stat block remain exactly the same when it transforms, apart from its size and appearance. This means he remains at 34HP, and regens 10HP per turn as usual.
No, this won't work for several reasons
There are several problems here...
Qualith is not the written form of Deep Speech. Deep Speech does not have a written form. It is the only language listed in the PHB that lacks a script used to write it down (see PHB/Basic Rules Chapter 4). Qualith is a unique, written-only language only used or understood by Mind ...
Treat the Dragon's CR as 20
In the specific example you give at face value the current CR seems appropriate, but I would argue given how the spell works and its effects that it was specifically designed to deter low level players and weaker creatures from entering. While the shape-changed dragon has some of the stats of a lower CR creature, it retains some ...
You cannot make equipment because you cannot change your statistics
We already have a Q/A which establishes that equipment (and thus clothing) are part of a creature's statistics: "What all is included in a creature's game statistics?"
The Shapechanger feature in question states:
As an action, you can change your appearance and your voice. [...] none of ...
No. The abilities the werewolf has in each form are listed in its stat block. From its Shapechanger ability: "Its statistics, other than its AC, are the same in each form," where statistics would include pack tactics.
No, a transmuter wizard is not considered a shapechanger
Shapechanger is a tag which is given to certain creatures.
The spell text of Moonbeam refers specifically to 'A shapechanger' not simply 'A creature with the shapechanger abilty'. Gaining your 10th level class feature as a Wizard Transmuter doesn't change you from a Medium humanoid (any race) to a ...
There are a number of cases in D&D where the exceptions to a rule are not stated.
This is where the "specific beats general" principle of interpretation becomes relevant. "It can use its action to polymorph [...] back into its true form" is a specific rule; "the vampire can't take any actions" is a general rule. So, a vampire in mist form that is not in ...
Looking over the GM moves, here are some ideas that come to mind.
Deal damage is simple, direct, but will get boring quickly.
Use up their resources could cause them to break something they were holding, wearing, or carrying during the transformation.
Turn their move back on them could get them stuck in a suboptimal form for a little while. As GM, I would ...
Use the Truth Like a Shibboleth
tl;dr The players ask straight forward questions and watch for a pain response.
Jackalweres Can be Discovered When Speaking the Truth.
The description of the jackalwere notes a non-magical way of discerning the creature's nature.
From the 5e Monster Manual (p. 93):
A jackalwere is born to lie, and perceptive creatures ...
Death Throes does not happen if you drop to 0 hit points
If you revert as a result of dropping to 0 hit points, any excess damage carries over to your normal form.
In other words, when you drop to 0 hit points you don't die, instead you directly revert into your normal form, so Death Throes does not take effect.
Death Throes might ...
Dragons change their physical characteristics, but not their cognitive capabilities.
Ancient Copper Dragons have the ability to change their shape (MM 110 edited for clarity) Dragons in general (MM 84-118) only gain the ability to change shape at the age category (MM 86) adult or ancient depending on their colour:
Change Shape. The dragon magically ...
No, they are not shapeshifters
Changelings can only change their general appearance, they can't completely change their form. No matter what form they take with their powers they are always a humanoid. They lack the shapeshifter descriptor which would be the main indicator.