If you cast a spell that targets a location while on a moving platform (say, a ship, or a train, or a flying castle) does it move with the platform?
Does it matter what kind of spell? For example, most cloud spells I would intuitively expect to stay in a the same position relative to the air, which means indoors they'd stay in one place, and outdoors they'd likely get carried away rapidly.
I'm pretty sure that if you've got a moving battle map, most DMs will have areas move with the map because anything else is annoying, but RAW doesn't actually address this afaik.
That would depend on what the spell is and what you're casting it on. A few examples.
Darkness can be cast either on an area or on an object that isn't being worn or carried. If it's cast on an area, the moving platform may move out of said area. If it's cast on the moving platform, it would move with the platform, because it states that it becomes an emanation originating from the object.
Fog Cloud and Stinking Cloud specify only a spot within range. Because they say nothing about objects, they would stay put regardless of what happens around them.
Cloudkill and Incendiary Cloud both specify they move 10 feet away from you each turn. They don't say anything about objects, so they function mostly like Fog Cloud and Stinking Cloud above, but the direction that's "away" from you might change from turn to turn. This could create some interesting interactions.
Basically: Each spell that creates an AoE will tell you whether or not it would move with a moving platform, and other details about how it may move. The RAW addresses this by being specific about object interactions when it's relevant.
Now hold on. Physics disagrees with a lot of that. Physics says that any physical thing is subject to relative speed and air resistance. For example, if you're inside a fully enclosed train car and drop a ping pong ball, the ping pong ball will fall at the same relative speed as the train, and to you, a passenger inside the train, it will appear to fall straight down. Likewise, a Fog Cloud would "stay put" inside the same fully enclosed train car.
However, if you're on an open-air platform, where the surrounding air is motionless while you are in motion, then if you dropped the same ping pong ball, the air resistance will dramatically slow the ping pong ball, causing it to appear to you, a passenger on the platform, to fall "backwards." Likewise, a Fog Cloud would be acted on by the same air resistance, causing it to appear to move backwards as the platform moves forwards. Technically, the relative starting speed of the cloud and the friction of the platform would cause the cloud to temporarily move forward, but you would barely notice. It bears mentioning that the speed of the platform might create enough air resistance to mimic the effects of a "strong wind," which would immediately disperse such spells, but that would be up to the DM to decide.
As to purely metaphysical effects, I think it's ultimately a DM call. I'd argue that metaphysics pretty closely mimics actual physics, so a Darkness spell targeting an area would be targeting the relative space as opposed to the static space, and that it would travel with you regardless of the movement of the platform, but that's largely because it's more fun than telling your party caster that they can't use any of their spells. Also, photons (and, thusly, the deprivation of photons) can't be subjected to any kind of resistance, so I'd argue it'd still work on an open-air platform.
Now hold on. Physics disagrees with a lot of that.
Something to remember: D&D is not a physics simulator. However, a lot of what you covered would be a reasonable way to run an encounter. At that point, it's the DM's call, and something players can bring up as part of an open, healthy discussion.
So, if you're casting, say, Moonbeam on an Eberron train, having the moonbeam remain stationary while the train moves everyone through the beam, causing you to more or less instantly sweep through the entire train (the train moves 30 mph or 264' per round) seems... unlikely to be intended behavior. For that matter, if you're on a rotating planet, having your moonbeam start sweeping west at several thousand feet per turn seems unintended, and if you're in a setting with orbital mechanics, the same goes to having it left behind by planetary movement at a few hundred miles per turn; stationary isn't really a sensible concept, you always have to ask 'stationary relative to what?'.
I always just leave the effect in place relative to the platform. It just over-complicates things to worry about it staying stationary while everything else moves around it. And it would drastically change the value of the spell, as something meant to have a long duration would often only be useful for one round. (As I'm writing that, I'm thinking, OK, that might be neat for one fight as a way to kind of force a change of tactics, but I still don't think it would be worth it.)
And I don't even want to think about what would happen if the moving object was something like a ship, which might be turning; not to mention bobbing up and down with the waves and then forcing the cloud to interact with the z axis.
The whole thing is just too much work in what seems like an effort to maintain realism, and it doesn't pay off enough in amount of fun you get for the amount of work.
...stationary isn't really a sensible concept, you always have to ask 'stationary relative to what?'.
Stationary with respect to the battle map, clearly :)
It's a fair ruling, and probably what most DMs would actually do, but leaves some holes (the actual reason I was thinking about this is because of an encounter involving a boarding operation against a moving spelljammer in the air. The spelljammer was the map since there's nothing about the air that's interesting terrain, but ...).
The question is really about what frame of reference a spell can or should use to establish its permanent location. Is it the surface of the planet? What if you are on a giant floating island drifting in a void? A big ship on an endless ocean?
Personally, I think it deserves an Arcana check based on the relation between the size and movement potential of the platform, and the size of the spell effect area:
Landmass-sized platform, automatic success.
Wagon-sized small platform and spell with effect that extends beyond that platform, impossible.
DC 10-35 for all the things in between. Harder for smaller or faster platforms. Harder if the platform moves over a bigger platform like a vehicle over land. Harder if the spell size approaches or exceeds the platform size.
On a fail, the spell anchors to the frame of reference of the planet/land/plane of existence, and the vehicle might move out of the effect.
Then even if you do manage to anchor a spell to the intended frame, it could be affected by the movement of the vehicle, so a cloud could be blown away if it not contained.
What does stationary even mean? The planet moves. Everything is always in motion.
Edit: I don't even know how to begin answering the poll questions.
Edit 2: The most consistent answer is the spell remains stationary (or moves as described) relative to the caster's frame of reference. But that does mean that if you're on the train in Eberron, the moonbeam moves with the train. But if you're not on the train, the entire train moves through it.
There is no one simple answer. There are too many variables to consider, which is why the next 100 comments will be people arguing back and forth about the most absolute minutae of RAW vs RAI.
It's not a situation that comes up often, so when it does, just use your common sense and make a ruling for that situation in that moment.
It does whatever the DM says it does (possibly using player input during session 0).
As others have said relative to what? In most cases I would use the battle map for simpliciy but for a cloud spell in open air I might say the deck of the ship or whatever moves though it, if the platform is moving very fast I could even rule the wind caused my the otion is enugh to disperse it (if Gust of wind would disperse it).
...stationary isn't really a sensible concept, you always have to ask 'stationary relative to what?'.
Stationary with respect to the battle map, clearly :)
It's a fair ruling, and probably what most DMs would actually do, but leaves some holes (the actual reason I was thinking about this is because of an encounter involving a boarding operation against a moving spelljammer in the air. The spelljammer was the map since there's nothing about the air that's interesting terrain, but ...).
I think it's the implicit ruling, i.e. what happens in absence of a ruling.
If the map is on the spelljammer, then that's the frame of reference. If the map is on the boarding ship(?), then that's the frame of reference. There aren't any established rules for multiple maps moving with respect to each other.
If there are walls between the spaces (like with the inside-a-train examples), you can avoid most of the issues, since the walls will tend to block effects and limit areas.
Yeah, it's all stationary to the frame of reference of the combat. This is a pragmatic answer.
I'd actually make an exception for Spelljammer, in that the SJ rules explicitly say that ships and other large objects have their own gravity, and so I'd rule that an AoE would always attach to the gravity plane. So if you're doing ship-to-ship combat and slap a darkness on the pirate ship's deck, the darkness moves, even though the frame of reference is space.
As for the moonbeam-train question, if the train's moving through the battle map, you can cast it so the train passes through it, but presumably the occupants of the train have full cover, so you don't get to zap them all.
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If you cast a spell that targets a location while on a moving platform (say, a ship, or a train, or a flying castle) does it move with the platform?
Does it matter what kind of spell? For example, most cloud spells I would intuitively expect to stay in a the same position relative to the air, which means indoors they'd stay in one place, and outdoors they'd likely get carried away rapidly.
I'm pretty sure that if you've got a moving battle map, most DMs will have areas move with the map because anything else is annoying, but RAW doesn't actually address this afaik.
That would depend on what the spell is and what you're casting it on. A few examples.
Darkness can be cast either on an area or on an object that isn't being worn or carried. If it's cast on an area, the moving platform may move out of said area. If it's cast on the moving platform, it would move with the platform, because it states that it becomes an emanation originating from the object.
Fog Cloud and Stinking Cloud specify only a spot within range. Because they say nothing about objects, they would stay put regardless of what happens around them.
Cloudkill and Incendiary Cloud both specify they move 10 feet away from you each turn. They don't say anything about objects, so they function mostly like Fog Cloud and Stinking Cloud above, but the direction that's "away" from you might change from turn to turn. This could create some interesting interactions.
Basically: Each spell that creates an AoE will tell you whether or not it would move with a moving platform, and other details about how it may move. The RAW addresses this by being specific about object interactions when it's relevant.
Now hold on. Physics disagrees with a lot of that. Physics says that any physical thing is subject to relative speed and air resistance. For example, if you're inside a fully enclosed train car and drop a ping pong ball, the ping pong ball will fall at the same relative speed as the train, and to you, a passenger inside the train, it will appear to fall straight down. Likewise, a Fog Cloud would "stay put" inside the same fully enclosed train car.
However, if you're on an open-air platform, where the surrounding air is motionless while you are in motion, then if you dropped the same ping pong ball, the air resistance will dramatically slow the ping pong ball, causing it to appear to you, a passenger on the platform, to fall "backwards." Likewise, a Fog Cloud would be acted on by the same air resistance, causing it to appear to move backwards as the platform moves forwards. Technically, the relative starting speed of the cloud and the friction of the platform would cause the cloud to temporarily move forward, but you would barely notice. It bears mentioning that the speed of the platform might create enough air resistance to mimic the effects of a "strong wind," which would immediately disperse such spells, but that would be up to the DM to decide.
As to purely metaphysical effects, I think it's ultimately a DM call. I'd argue that metaphysics pretty closely mimics actual physics, so a Darkness spell targeting an area would be targeting the relative space as opposed to the static space, and that it would travel with you regardless of the movement of the platform, but that's largely because it's more fun than telling your party caster that they can't use any of their spells. Also, photons (and, thusly, the deprivation of photons) can't be subjected to any kind of resistance, so I'd argue it'd still work on an open-air platform.
Something to remember: D&D is not a physics simulator. However, a lot of what you covered would be a reasonable way to run an encounter. At that point, it's the DM's call, and something players can bring up as part of an open, healthy discussion.
So, if you're casting, say, Moonbeam on an Eberron train, having the moonbeam remain stationary while the train moves everyone through the beam, causing you to more or less instantly sweep through the entire train (the train moves 30 mph or 264' per round) seems... unlikely to be intended behavior. For that matter, if you're on a rotating planet, having your moonbeam start sweeping west at several thousand feet per turn seems unintended, and if you're in a setting with orbital mechanics, the same goes to having it left behind by planetary movement at a few hundred miles per turn; stationary isn't really a sensible concept, you always have to ask 'stationary relative to what?'.
Stationary with respect to the battle map, clearly :)
I always just leave the effect in place relative to the platform. It just over-complicates things to worry about it staying stationary while everything else moves around it. And it would drastically change the value of the spell, as something meant to have a long duration would often only be useful for one round. (As I'm writing that, I'm thinking, OK, that might be neat for one fight as a way to kind of force a change of tactics, but I still don't think it would be worth it.)
And I don't even want to think about what would happen if the moving object was something like a ship, which might be turning; not to mention bobbing up and down with the waves and then forcing the cloud to interact with the z axis.
The whole thing is just too much work in what seems like an effort to maintain realism, and it doesn't pay off enough in amount of fun you get for the amount of work.
It's a fair ruling, and probably what most DMs would actually do, but leaves some holes (the actual reason I was thinking about this is because of an encounter involving a boarding operation against a moving spelljammer in the air. The spelljammer was the map since there's nothing about the air that's interesting terrain, but ...).
The question is really about what frame of reference a spell can or should use to establish its permanent location. Is it the surface of the planet? What if you are on a giant floating island drifting in a void? A big ship on an endless ocean?
Personally, I think it deserves an Arcana check based on the relation between the size and movement potential of the platform, and the size of the spell effect area:
Landmass-sized platform, automatic success.
Wagon-sized small platform and spell with effect that extends beyond that platform, impossible.
DC 10-35 for all the things in between. Harder for smaller or faster platforms. Harder if the platform moves over a bigger platform like a vehicle over land. Harder if the spell size approaches or exceeds the platform size.
On a fail, the spell anchors to the frame of reference of the planet/land/plane of existence, and the vehicle might move out of the effect.
Then even if you do manage to anchor a spell to the intended frame, it could be affected by the movement of the vehicle, so a cloud could be blown away if it not contained.
What does stationary even mean? The planet moves. Everything is always in motion.
Edit: I don't even know how to begin answering the poll questions.
Edit 2: The most consistent answer is the spell remains stationary (or moves as described) relative to the caster's frame of reference. But that does mean that if you're on the train in Eberron, the moonbeam moves with the train. But if you're not on the train, the entire train moves through it.
There is no one simple answer. There are too many variables to consider, which is why the next 100 comments will be people arguing back and forth about the most absolute minutae of RAW vs RAI.
It's not a situation that comes up often, so when it does, just use your common sense and make a ruling for that situation in that moment.
D&D is a game of imagination. Figure it out.
Anzio Faro. Protector Aasimar light cleric. Lvl 18.
Viktor Gavriil. White dragonborn grave cleric. Lvl 20.
Ikram Sahir ibn-Malik al-Sayyid Ra'ad. Brass dragonborn draconic sorcerer Lvl 9. Fire elemental devil.
Wrangler of cats.
It does whatever the DM says it does (possibly using player input during session 0).
As others have said relative to what? In most cases I would use the battle map for simpliciy but for a cloud spell in open air I might say the deck of the ship or whatever moves though it, if the platform is moving very fast I could even rule the wind caused my the otion is enugh to disperse it (if Gust of wind would disperse it).
I think it's the implicit ruling, i.e. what happens in absence of a ruling.
If the map is on the spelljammer, then that's the frame of reference. If the map is on the boarding ship(?), then that's the frame of reference. There aren't any established rules for multiple maps moving with respect to each other.
If there are walls between the spaces (like with the inside-a-train examples), you can avoid most of the issues, since the walls will tend to block effects and limit areas.
Yeah, it's all stationary to the frame of reference of the combat. This is a pragmatic answer.
I'd actually make an exception for Spelljammer, in that the SJ rules explicitly say that ships and other large objects have their own gravity, and so I'd rule that an AoE would always attach to the gravity plane. So if you're doing ship-to-ship combat and slap a darkness on the pirate ship's deck, the darkness moves, even though the frame of reference is space.
As for the moonbeam-train question, if the train's moving through the battle map, you can cast it so the train passes through it, but presumably the occupants of the train have full cover, so you don't get to zap them all.