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Since reverse gravity is a concentration spell, what would happen if someone casts it, and then an enemy casts meteor swarm on the area in which reverse gravity is in place?

Now, meteor swarm is described as instantaneous, but still specifies it's blazing orbs of fire plummeting to the ground, as meteors do. So, would the reverse gravity spell prevent the meteors from working, decreasing how they work, or have no effect?

I'd like both an answer that makes the most sense with the rules, as well as an answer that would make the most sense in general for a DM to implement. Personally, I was thinking that the fairest way of doing it would be to half the damage from them.

(This could also be asked for other spells that involve hurling objects; it's just meteor swarm, in particular, that I was wondering about.)

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  • \$\begingroup\$ Welcome to RPG.SE! Take the tour if you haven't already, and check out the help center for more guidance. \$\endgroup\$ – V2Blast Mar 28 at 19:07
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Simple answer: No

Reverse Gravity affects creatures and objects, and a spell is neither (though a spell may conjure or create a creature or object).

And, as you say, any spell with a duration of instantaneous effectively happens without any chance for something to affect it unless specifically noted.

A more 'physical' argument against Reverse Gravity affecting Meteor Swarm or similar spells is that the spell creates the blazing orbs of fire with enough force and momentum for them to reach their targets before gravity can have much of an effect.

After all, even without Reverse Gravity, a spell that launches something at a target doesn't have to worry about gravity pulling it to the ground before it reaches the target!

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  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. \$\endgroup\$ – doppelgreener Mar 28 at 16:31
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    \$\begingroup\$ Also worth noting that the spell is evocation so the in game effect is to cause damage and all else is simply special effects. If it were a conjuration spell, then the effect would be to call something into existence, at which point it becomes an object that is affected by the world like any other. The "meteors" from Meteor Swarm are not objects, they are simply cosmetic effects of magical energy being directed to cause damage. The only ways to change that are to either interfere with the magic - counterspells, etc. - or to be immune/resistant to the damage type. \$\endgroup\$ – cpcodes Mar 28 at 16:35
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    \$\begingroup\$ @cpcodes No, 5e doesn't have "special effects". That isn't flavour text. They do plummit to the ground, they are blazing orbs of fire. They aren't "merely cosmetic". 5e doesn't have flavour text. For example, if there is no ground at the point you select, the spell doesn't work (the spell only creates orbs that plummet to the ground at the points you select; again, not flavour text, all text in spells is actual game rules), \$\endgroup\$ – Yakk Mar 28 at 17:59
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Alright, this is a case where Jeremy Crawford's mantra applies to all Rules as Written answers.

Spells do Exactly What They Say

Reverse Gravity

7th level transmutation

This spell reverses gravity in a 50-foot-radius, 100-foot high cylinder centered on a point within range. All creatures and objects that aren’t somehow anchored to the ground in the area fall upward and reach the top of the area when you cast this spell. A creature can make a Dexterity saving throw to grab onto a fixed object it can reach, thus avoiding the fall.

If some solid object (such as a ceiling) is encountered in this fall, falling objects and creatures strike it just as they would during a normal downward fall. If an object or creature reaches the top of the area without striking anything, it remains there, oscillating slightly, for the duration.

At the end of the duration, affected objects and creatures fall back down.

Gravity is reversed, things fall up. Cool. You're either falling to the ceiling or hanging from the floor. Right? Alright, we all agree here.

Meteor Swarm

9th level evocation

Blazing orbs of fire plummet to the ground at four different points you can see within range. Each creature in a 40-foot-radius sphere centered on each point you choose must make a Dexterity saving throw. The sphere spreads around corners. A creature takes 20d6 fire damage and 20d6 bludgeoning damage on a failed save, or half as much damage on a successful one. A creature in the area of more than one fiery burst is affected only once.

The spell damages objects in the area and ignites flammable objects that aren’t being worn or carried.

Flaming orbs appear and plummet toward the targets. It doesn't say:

  • Which gravity it used
  • Where the orbs appear
  • What inertia they already have from wherever they were pulled.

They appear and plummet toward the targets. If that means they appear "beneath" them and fall up or above them and fall down or if they magically fall sideways -- because magic -- then they fall sideways. Whatever direction they plummet, they plummet at the targets.

So, if you're hanging from the floor or fell to the ceiling, maybe they appear "above you" closer to the floor than you currently are and traveling in your direction, or they appear already having a huge amount of inertia to overcome the effects of the reverse gravity spell. I don't care what you do narratively to convince yourself and your players why it happens -- the spell says what it does.

Points, not Creatures

The "a point you choose" don't have to be on the ground. It can be in a person's gut or head or whatever. The spell is instantaneous so the person won't have moved by the time the meteor gets there. Unless they have a reaction to use a spell to get out of the way, which, I suspect, is one of the reasons the target is points and not a creatures. Another is so that you can use it on objects. You can't magic missile or eldritch blast a door, but you can meteor swarm it. (Did this really need saying?)

But Physics...

If you're a strict follower of Rules as Written, or even if you aren't, part of the job a DM has is to make the rules make sense in context. Find a flavor or spin that makes the game mechanics work for the understanding of the surrounding environment and physics. So those meteors already have inertia from wherever they were conjured from that is greater than the reverse gravity field, or they conjured closer to the floor so they plummet "upward" toward the characters. "Physics" isn't a good reason to make someone, NPC or PC, lose a 9th level resource for nothing... However...

If reverse gravity is already up, and meteor swarm is cast -- no I'm not going to let a 7th level spell mangle a 9th level casting for no good reason because I think our world's physics should apply to a world where where flaming orbs can just appear, a person waving their arms and saying words can reverse gravity, an expensive enough gem can be used to bring back someone from the dead, and dragons are a real threat to local commerce... D&D is simulations, and our descriptions of what happens as a result of the mechanics is what makes anything in the world believable or not.

Rules as Cool

The rules aren't everything. If a PC readies a held casting of reverse gravity with a trigger of meteor swarm, that's pretty clever. And the order can make a narrative to why the "physics" works and rewarding the player for his creativity and his risk of wasting a 7th level slot if meteor swarm isn't cast is a perfectly acceptable narrative tool. Don't have an NPC do it, but allowing a PC to do that once is not a problem. That said, they'll have to fall 85 feet to get out of the way -- which will still be a huge amount of damage.

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  • \$\begingroup\$ To be clear, you are ignoring the "to the ground" part of the spell rules because you feel it wasn't intended? Or are you aruing that the "ground" part is just fluff text? I'm just looking for a clarification about that point. \$\endgroup\$ – Yakk Mar 28 at 18:36
  • \$\begingroup\$ Neither actually. In a comment that was since removed I explained that "ground" has been ruled to not necessarily mean "ground" by Jeremy Crawford a couple of times. I just didn't want to go look for it, so I argued that "ground" isn't the meat of the intent of the spell. I only added the ground section because of comment (also since remonved). \$\endgroup\$ – J. A. Streich Mar 28 at 18:54
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    \$\begingroup\$ Overall, a great answer. The fairness of spider climbing example is a bit weak, I feel. The 2nd-level invisibility can defeat the 9th-level power word kill if the caster can't see through it. The 1st-level tasha's hideous laughter can end the 9th-level invulnerability on one failed save. Still, +1 for a thorough analysis. \$\endgroup\$ – Red Orca Mar 28 at 20:30
  • \$\begingroup\$ Really enjoyed reading through this, though I feel like not everything you mentioned was entirely just (Streichs comment being an example) Also, no, the room isn't that high, it would be an open space. \$\endgroup\$ – DMs Popped Cherry Mar 28 at 21:10
  • \$\begingroup\$ Seems like you're making a huge assumption that the battle is indoors. An outdoor battle would easily allow for the full 100-foot cylinder to be of concern. And the grabbing save would easily allow for some creatures to be on the ground and some to be at the top of the cylinder. \$\endgroup\$ – jpmc26 Mar 29 at 8:06
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The blobs of fire created by Meteor Swarm would be affected by Reverse Gravity

As mentioned Meteor Swarm has a duration of instantaneous. For the purposes of the rules instantaneous has a specific meaning in relation to the spell duration:

Instantaneous

Many spells are instantaneous. The spell harms, heals, creates, or alters a creature or an object in a way that can't be dispelled, because its magic exists only for an instant.

The instantaneous duration refers to the creation of the objects in the spell, the "effect" of the spell. Importantly it does not refer to the resolution of those effects (and in particular the damage caused by the effect).

In the case of Meteor Swarm the effect it creates is

Blazing orbs of fire plummet to the ground at four different points you can see within range.

The key word here is "plummet". This is not a defined game term, thus we must check what it's natural meaning is in English.

Plummet means

to fall very quickly and suddenly:

House prices have plummeted in recent months.

Several large rocks were sent plummeting down the mountain.

She plummeted to the ground.

Falling is something that is explicitly affected by Reverse Gravity

All creatures and objects that aren't somehow anchored to the ground in the area fall upward and reach the top of the area when you cast this spell.

How are objects defined in the rules?

DMG > Running the Game > Objects

For the purpose of these rules, an object is a discrete, inanimate item, like a window, door, sword, book, table, chair, or stone, not a building or vehicle that is composed of many other objects.

  • It is discrete (each orb is described as a single item made of a single substance)
  • It is inanimate
  • It is not composed of many other objects (each orbs isn't composed of other small objects, they are a contiguous whole)

The orbs of fire are pretty clearly objects and thus would be affected by Reverse Gravity when they come into the area of effect of Reverse Gravity.

Even if they are not objects, but are a contiguous whole made up of smaller objects, it doesn't matter. Each of the constituent objects would be affected by the Reverse Gravity field as the orbs of fire are not "anchored to the ground".

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  • \$\begingroup\$ Comments are not for extended discussion; this conversation has been moved to chat. \$\endgroup\$ – doppelgreener Mar 28 at 16:33
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    \$\begingroup\$ @Akixkisu the room expired and got soft deleted, so now it's only visible to 10k+ users. You will see this a lot. \$\endgroup\$ – doppelgreener Jun 13 at 16:35
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Reverse gravity could deflect arrows, but not meteors.

Physics-wise, reverse gravity only affects a 100 ft-high cylinder. Meteors come in around 17 km/s, which means that the 100 ft-high cylinder would do nothing.

More precisely, we've got initial velocity vi=-17 km/s, acceleration a=+9.8 m/s2 (with reverse gravity), and displacement x=-100 ft=30.48 m. Using vf2=vi2+2ax, we get vf=16.9999824 km/s, or more usefully, vf/vi≈99.9999%, meaning the final velocity is 99.9999% the original. So the damage should be reduced by one part in one million.

This assumes reverse gravity does as it says, as compared to amplifying gravity beyond normal earth (e.g.: instead of g→-g, we have g→-200g). To make the meteors come to a stop, so they barely touch the ground, they'd need to have a force of gravity about 500000 times stronger than our own. Even only halving its speed would take a force of gravity 360000 times stronger than our own. With that much force, they'd be crushed by the acceleration and die. (Anything beyond about 50Gs is lethal.)

So either way, they're toast.

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    \$\begingroup\$ D&D is not a physics simulator \$\endgroup\$ – illustro Mar 28 at 13:55
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    \$\begingroup\$ Moreover you are making some pretty stark assumptions on how the magic spell works to make objects fall upwards. D&D is a world where conservation of momentum simply doesn't apply because magic. \$\endgroup\$ – illustro Mar 28 at 14:05
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