- cross-posted to:
- dnd_memes@lemmy.world
- cross-posted to:
- dnd_memes@lemmy.world
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I’m here for it, if they earn it. I love players having OP bullshit magic, but it’s no fun unless they work for it. Changing magic artifacts isn’t easy; everything about them is intrinsic to how they work. This is why wizards are useless without their cookbooks detailing every little step, and sorcerers always get weird side effects with their “fuck it, we ball” casting. This is where you tell the players that they’re going to need to return to the forge that cast the ring, or find a way to get help from someone high up in the jeweler’s guild or something like that. Sure, you could always try to DIY your magic canon, but you’re basically doing fantasy electrical engineering with vibes and a screwdriver; ask yourself, what could go wrong?
What could go wrong? The gun/shooting makes the size and effect of the field unstable. Weird effects on size and momentum and direction, causing damage and hit chance reduction based on rolls you select every shot. Also, after about three shots the field it unstable enough to reach into the barrel and ruin it by having the next ball expand inside, jamming and destroying the weapon.
I was thinking they could do it as many times as they wanted. But every time they use it that way they have to roll a d20 to see if they broke it. And then they have to roll Con to see if they took damage firing it, and whether they remain standing.
The problem is with this specific case. A 12 pound cannonball is going to end a lot of fights before they even start. There’s not a lot of ways to have non boss enemies take that kind of projectile and say they aren’t dead right away.
Either that or come up with some flavor for it not coming back to full size/weight. Effectively allowing them to have a +1/2/3 weapon. I’m all for giving players stuff that makes them feel powerful and giving them fluff fights for the same reason. But some stuff really does need push back.
That’s how I run my table. I am a merciful god, but also a petty god if you reach for the heavens a little too hard. D&D magic already screws with thermodynamics to the point where free energy just exists, so I try to draw a line just short of where anyone figures that part out.
In the back of my mind, I’m always asking the question: “Why wasn’t this loophole exploited in the world already?” That usually prompts a suitable response.
you’re basically doing fantasy electrical engineering with vibes and a screwdriver; ask yourself, what could go wrong?
Exactly. In the situation that OP raises, I ask myself: “Does Newton or Gandalf win this argument?”
In the situation that OP raises, I ask myself: “Does Newton or Gandalf win this argument?”
Exactly. Does the bullet remain moving at the speed it already was? Or does the conservation of momentum require that it slows as it grows larger (and heavier)? If so, it would basically be useless as a weapon, because a handheld firearm couldn’t exert enough force to actually fire a cannonball any effective distance; At most, it can only exert as much force as the recoil exerts on the character. And a 12 lb cannonball would get rolled across the floor by the recoil, but not fired across the room.
I’d probably rule it’s somewhere in between, because “rule of cool” is just plain fun and that’s why we’re all playing the game. Having it be a full blown “it fires cannonballs at full speed across the room” weapon is obviously super broken. But maybe I rule that the bullets aren’t near the ring long enough to fully regrow, but it gets a +2 modifier to damage because you’re effectively firing rifle sized rounds with a handgun.
Or maybe I rule that they slow down as they grow, but the spell takes some time to wear off, which limits the maximum range and effectively makes it a devastating close-up weapon, but relatively useless at longer distances.
The point is that the players worked for it, and get some sort of payoff. Even if it’s not a complete game-breaking reward.
So does the thing use a portable hole for a magazine or something? Also, does the shrink spell reduce the weight too?
Enlarge Reduce specifically says the weight changes by 1/8th every time you go down a size category.
Fun fact, 1/8th of a 12 pound naval cannonball is 1.5 pounds. Translating in modern terms to about a 40mm projectile. Even shrunk these would be one hit kill projectiles in real life.
Another fun fact, 5 tons of cannonballs would be just under a thousand 12 pound cannonballs.
Third fun fact, their party now needs a way to transport 1,300 pounds of this guy’s ammo.
I think the party missed another interesting (albeit elaborate) use.
Find a large pointy rock. Shrink it down to the size of a small arrow head. Attach it to an arrow shaft such that the head will slide off the end of the shaft without too much effort (staying embedded in the target). Have the rogue launch it at the big bad, then have the barbarian or monk punch the arrow wound while wearing the ring.
This is creative. I like this.
I love how everyone is discussing the physics of a cannonball gun DIY setup in a game where magic can instantly teleport people or turn a person into a huge dragon.
I’m not complaining, I just find it amusing.
Point is well taken, but D&D magic doesn’t take physics off the table, it violates physics within strict limits. Mundane physics still operates. As a DM a good reason I can think of for invoking physics in cases like this is that the player’s plan depends as much on physics as it does on magic, and I don’t think their cannonball trick would work. The gunpowder imparts the same momentum to the shrunken, diminished-mass cannonball as it would to a regular bullet. When the cannonball’s original size and mass are restored, it still has that much momentum - which I imagine will carry it a few feet.
Fortunately my game group includes a very smart player with a master’s degree in physics, who is very quick at computing such things. I would absolutely trust her estimate of how far the cannonball would go.
Inversing this gets really fun: enlarge spell on a tungsten/mithril bearing or toothpick. Pack enough charge to fire it out of an actual piece of siege equipment, hello nearly relativistic projectiles. Ship or battlement mounted rods from God.
"We strategically position our ship to ensure the flight path of the projectile happens in 6 second intervals, allowing for a near perfect rhythm of enlarge chanting. We keep three wizards and a wild magic sorcerer near each of our cannons.
We don’t lose fights often, no, why do you ask?"
Unfortunately after a single fire the force tosses the ship onto its side and is sinking
Firing even a 42lb cannon wouldn’t capsize a decently large ship. A 42lb projectile at 1700 ft/s carries like 425 million joules of energy. Then shrink that mass down from 42lbs to 0.5 lbs and let conservation of energy multiply the and whatever is in its flight path is going to have a really bad day. Like a “half a pound traveling at 0.6% of C” level of bad day.
With magic metals like mithril you can probably make a siege cannon of at least double the poundage. Modulate the load and use a tungsten wire instead of a toothpick, and you make a plasma weapon. You would need wizards dedicated to calculating the firing solutions to ensure you don’t miss your shots. Einstein would be the deadliest mother fucker on the Sword Coast.
Well, the cannon only needs to produce enough force to move a tiny cannon ball really fast.
The 6 second interval is to match the in game fight sequences, implying that the enlarge spell would finish casting as it impacts the enemy ship. All of that momentum suddenly comes to a grinding halt as the weight suddenly changes and the cannon ball rips the enemy ship to shreds
I came here to point out exactly this: If you only shrink the ball, without reducing its size, well… you’re gonna have problems carrying the ammo.
As a DM, I think I would let them both shrink and reduce the mass, and wait till they fired the weapon before invoking “conservation of momentum” and declaring that the cannon ball drops to the ground after about a meter.
Dunno about 5e etc. but in 1e, which I still play & DM, Enlarge and its reverse affect both the dimensions and mass of an object. So the cannonballs could be reduced to a mass a gun could shoot.
Yeah, but D&D also has spells and potions of shrink / enlarge that don’t make players start drowning in atmosphere their lungs are too small to breathe or collapse under their own weight due to square cube law restrictions, so there’s definitely some magical physics at work in there.
You’re right, it’s very wonky, but that doesn’t validate not caring about physics at all, and the intellectual exercise of working it out is fun - which is the whole idea.
Well in that case, the reverse would also be true. So my barbarian can throw a cannonball at someone. How about if the mage readys the shrink spell to target the cannonball just as it leaves my hand? Conservation of energy would dictate that:
Decisions like these are what makes TTRPGs so fun, and I enjos every minute of these sort ot discussions.
Throwing a shrunken cannonball would work the same as shooting it out of a gun. If you throw an object that weighs one ounce at the time, it flies away with the amount of energy it took to accelerate an object that size to whatever velocity you give it. When the shrinkage magic stops, its mass returns to normal. This doesn’t change the amount of momentum the barbarian or the flintlock gave it. Think of it this way - if you get magically shrunk and you pick a flower, when the magic stops and you grow back to normal size the flower doesn’t also grow. It wasn’t affected by the magic and isn’t affected by the magic going away. Neither is anything else you acquire while shrunk, like momentum.
I see people make comments like this about shows, movies, etc. and I’ve never understood this line of thinking. I generally expect things to work the same as they do in real life unless it’s explicitly explained otherwise. Not sure if I’m the odd man out in thinking that way or what.
you sorta said it but an exception is places like the fae wilds, where you assume physics is only barely present enough to hold your organs together (hopefully)
No, you’re right IMO. Just because something is different from our world doesn’t mean all logical consistency is off the table. This idea is called versimilitude.
Verisimilitude
I had to look this up and I’m very surprised this is a borrowed word in English, at first glance I would assume it’s an evolution of “very similar to”
I think this ring would be great for handling magic items without being affected by them. Safe way to put something sketchy looking in a sack for later study.
Doesn’t the ring remove the magic though? That seems to be how OP’s cannonball gun would work. Otherwise they’d shrink back down after passing through the field.
I had to look this up: you are correct. The RAW on this is pretty clear: It’s a suppression field alright, and not a cancellation effect.
So, it’s probably more useful for wielding a cursed weapon or handling magical traps. It would also be great at disguising magic items from detection under pretty specific circumstances. All-in-all, just the thing a thief or rogue would want in their toolbag.
if the ring permanently ends magical effects that enter its area of effect, that’s unusual and probably has a bunch of unexpected uses.
It it merely suppresses magical effects in its area, I guess the projectiles would briefly return to full size when in the anti-magic field, and return to small size afterwards? Doesn’t seem very effective unless you like point blank someone.
“Cannonball Punch” sounds like a fun move, though.
It wouldn’t work on a magical lock if you had to hold it up to it all the time
…what? With the exception of mage hand legerdemain, you’re typically very close to locks you’re picking. If it made an anti-magic field like 6" from the ring, that would be perfectly fine for picking the lock. Ring is on hand, lockpicks are in hand, magic lock is disabled.
With the exception of mage hand legerdemain, you’re typically very close to locks you’re picking
Even touching them with your hands or with the tools in your hands, I’d say. And thieves tools aren’t like several feet long or anything.
I imagine that the momentum would be conserved. So if the rifle normally shot a 30 gram ball at 300 meters per second, it would shoot a 5 kilogram ball at around 23 meters per second.
- The larger size and lower speed of the cannon ball would likely reduce the range.
- The larger size of the projectile would spread out the impact causing reduced damage.
- The ballistics would be significantly different making it far harder to hit with.
This is how I would do it in my game:
- Reduce the damage from 1d12 to 1d10
- Change piercing type to bludgeoning
- Reduce range from 40/120 to something like 20/60
- Add knockback of 5 ft to medium targets or 10 for small
The really neat thing would be shooting non standard rounds that wouldn’t be possible from a musket like incendiary or smoke rounds.
This exact mechanic is present in the Misborn book series. I don’t want to give spoilers because I recommend the books so highly, but I love the hard science nature of the way the magic system interacts with physics.
Searching Misborn gives me too many different results. Which one?
the books are the mistborn trilogy by Brandon Sanderson, and it’s second trilogy; wax and wayne.
the physics bit is central to both, but it’s a bigger focus in the second trilogy.
highly recommend all of them!
and for more wacky ideas…well, the entire rest of the cosmere series! especially tress of the emerald sea, which is largely standalone, but contains quite a bit of in-universe lore…
Ah, I wondered if it might have been a typo since “mistborn” seems like a more plausible word. I’ve been meaning to get around to Sanderson since forever, but I didn’t do any reading for the longest time, and I’ve been on a big sci-fi kick since starting up again because I’m mostly interested in stories that use novel premises to examine issues like human rights and the nature of consciousness/life, etc. I’ve felt like fantasy is too meaningless adventure-y? Not enough induction of personal growth. But I’m in the middle of The Magicians right now, and that’s really proving me wrong, and also there was Tehanu. That was a hard book to read because it was so real.
Anyhow, thanks to you both.
Have you been through the 3 body problem series by Cixin Liu? Soooo good. Loads of the stuff you mentioned.
the cosmere series as a whole (of which the mistborn saga is a part) reeeeaaaally straddles the line between sci-fi and fantasy;
it’s all a kind of “hard fantasy”, where all of the powers that people use are strictly limited by a certain energy source (don’t want to spoil anything here, even though it’s a kind of unimportant detail overall).
so, in the mistborn saga for example, people swallow certain metals and use those metals to power certain abilities, depending on the metal, which uses up said metal. if it runs out, there’s no way to power those abilities anymore. and it DOES run out, it’s very much finite.
so if you like sci-fi, especially more on the hard sci-fi side, and have been enjoying some fantasy lately, i think it might be right up your alley! ;)
Love his magic systems. How’d you like stormlight 5? I balled.
I think damage reduction would be even more than that. The damage a projectile does to a target is directly related to its kinetic energy which is calculated as e = ½mv². So when you increase mass but reduce velocity you also reduce the damage by the square of the difference in velocity (I think). As long as the damage just relies on the physics of the projectile and not magic, that is.
I was assuming that the total energy would be maintained (In this case 1350 joules) and thus the damage should be the same if weren’t spread out. It has been 20+ years since I has to do any of that math so I could be wrong about any of that. And since the only paper that was handy happened to be an envelope I guess it was technically back of the envelope math. :)
Wouldn’t it dispell the magic before it got to the ring? So your gun just exploded and your ring is now somewhere downrange?
You’d have to mount it on a wire a bit past the end of the barrel, or custom create a barrel that expands toward the end. Depends on whether dispelling the magic is an instant transformation, or if it “grows” at some rate.
If you can shrink and expand stuff instantly, the thing getting bigger or smaller is the least useful part of that spell. You wouldn’t even need gunpowder to launch stuff, put a shrunk cannonball against a wall, expand it, hope the wall holds and it’s the cannonball that has to accelerate to light speed to not be in the same place as the wall. Or get a giant explosion, that’s more likely.
That does raise some interesting questions. To break as few laws of physics as possible, we can assume there’s no truly “instant” transformation. The question then becomes how quickly the transformation happens, and whether the transformation is linear with respect to radius, volume, or mass.
I feel like Randall Munroe would have a good answer.
If it dispels magic before it gets to the ring it’s going to be an issue…
Yep, and someone casting Dispel Magic on your gun would effectively ruin it, if it were loaded.
Would be fun watching him each time he carefully loaded it too… Probably a broken toe or two if he isn’t careful :)
Guns in dnd aren’t inherently magic actually.
Yeah, and if a regular gun is loaded with magically shrunken cannonballs and that magic is dispelled…
Yeah, if its range is enough to dispel a lock, then it must be at least an inch. So the cannon ball grows while an inch down the barrel.
Meme is still correct though as that’s my face while calculating what to change so they don’t TPK or something when they try it on the next encounter…
Rogue fires gun. Cannonball grows and shatters the gun. Gun pieces fall to floor in front of rogue. If you look, the ring is still in the wreckage, and still usable. Enemy spends a turn just looking at the rogue in amusement. Turn after goes as usual.
If a cannonball just sprouted in a gun barrel, the gun is gone and the hands that held it probably are too. There should be so much shrapnel
They would have gone all in on this strat and left themselves open for shenanigans.
Or decided to test it inside or something.
So that is engineering. Is this character an engineer with knowledge of magic, physics and mechanics?
It’s fine and easy for a player to think in term of game mechanics. But the actual process is not so goofy. And the character is not the player. The dice decide after that.
I dunno sounds like the only even vaguely engineering part is glueing a ring to the end of a pistol? If that’s considered out of the box clever enough to require a check I can only assume D&D takes place in the systemic lead poisoning dimension.
I would hope they put the ring on a stick so the bullet-size cannonball doesn’t enter the antimagic field until it clear the barrel - otherwise it would break the barrel open. But even if they did that I don’t think the scheme would work, because when the cannonball’s original mass is restored it would have the same momentum the gunpowder gave it when it had the mass of a bullet, which wouldn’t carry a cannonball very far.
I think the engineering part kicks in once the cannonball leaves the ring, or maybe around the mass of the shrunken ball. If the cannon ball retains it’s mass in it’s shrunken size does the gun have enough power to move it? If it does, then the gun is a ship cannon already, just a convenient size. If it doesn’t and can only shoot because the balls are as easy to fire as regular shot, then as soon as the ball exits the ring it is a cannonball being moved with the force of a small shot and likely drops to the ground an inch or so past the muzzle.
That’s my take on the cannonball as well. Being diminished reduces both its size and mass, so when restored it should have the momentum gunpowder gives a bullet. I’m guessing it might go a couple feet. But this is so interesting I’m gonna ask the player in my group who has a masters in physics how far she thinks it would go.
Many of the things we take for granted as obvious these days were anything but until recently. Take bolt cutters for example. The compound lever that let’s them function so well seems like something that would have been around for centuries, but in reality wasn’t something that was widely used/understood until the 1890s when they were marketed as a wonder tool.
On the other hand, this is a game and should be fun regardless of how anachronistic it is at times. At least as long as the witch/duck proportionality is maintained. There has to be at least some realism.
If it is a muzzle loader, no you don’t.
I suppose you’d have to remove the ring while loading in that case?
Good way to lose the ring.
Then segue into smeagol rp.
Because I hate fun, I assume that the people in a fantasy world aren’t all fools so if there’s an application of magic that seems obvious but isn’t already happening in the setting, there’s a good reason for that.
There’s also the rule of “if you can do it, so can NPCs”. Even if your character has thought of something no one in the universe has thought of before, word will get around.
I have it as: “cool idea, i’ll let you get away with it once. Start abusing it and all the NPCs start using it.” works pretty good.
This is a good take, but it partly depends on the setting. Specifically, if these magic artifacts are fairly rare and valuable (even something meager like this ring), it’s entirely possible that people haven’t explored that kind of application of magic. It could also be viable if there are very few inventors/scholars in the setting.
In any case, the conservation of mass thing another commenter mentioned would make this less viable, so you’re right on the money. That being said, laws of physics can be bent for rule-of-cool if that’s your table. Personally, if I were DMing it, I’d probably try to find a way to balance between realism and making their research process hilarious and/or dangerous, with the end result being them producing something useful but not gamebreaking (e.g., you can carry and deploy the cannonballs, but the gun doesn’t really fire them, but in combination with a method of flight, could still be awesome–or they apply this method with a large boulder and have that to work with instead).
Or, if you want to shut it down, the plan works, but since the magic effect has a range, to ball begins expanding before it makes it to the ring, taking the end of the barrel and the ring with it. If the ring is indestructible the character has to go on a search for the ring at the point of impact every time, it i expands within the ring, meaning you have a canon ball that explodes at the end of your gun with shrapnel, or you have to melt the ball down to retrieve the ring downrange.
Based on the text in the original post, I’m guessing that table ruled that the transformation took enough time for the ball to exit the gun. If not, mounting the ring out a little ways from the end of the barrel is an easy enough solution.
Your ‘timing’ thing would probably work, but if not, mounting the the ring away from the gun would only protect the gun, not the ring. I could see a timing or slowed effect could allow the ball to pass through before it expanded
Sounds as if you play as most unimaginative character that does everything in a dullest way possible. What’s the point of playing tabletop then? I mean half of the fun of tabletop rpgs is exploring the possibilities and creativity (for me).
The vibe I like is “gritty action movie”. Some people prefer something zanier.
Would the momentum stay if the mass increases?
Lol the ball just falls out the end like a defective Acme gun
As another poster mentioned, this is likely the reason this isn’t already done in the fantasy setting. Either the mass is the same (in which case your flintlock isn’t going to launch it terribly far) or the mass changes and it would reduce momentum.
That being said, it’s still a useful way to transport cannonballs, and could still be quite useful. Just not quite a “free” Catapult spell on demand.
If the mass increases after the ball is already moving, then velocity should be conserved and momentum would increase with the mass. That breaks all kinds of physics rules, but this is DnD in a magical universe, there are worse violations going on.
Sorry, I should say that the momentum is conserved, but it would affect the velocity (that is, the overall kinetic energy is the same, which means velocity has to drop by an equal factor to conserve energy). It would be similar to if the extra mass were to be suddenly tethered to the bullet, which would understandably slow it down.
That being said, it’s D&D and people can rule however they want.
Why assume a conservation of momentum?
Let’s do a quick thought experiment. Let’s say you’re tossing a cannonball in your hand, and the mage shrinks it just as it leaves your hand (maximum momentum). If momentum is conserved, the cannonball would have to dramatically increase speed to conserve momentum.
Example data/assumptions:
- if tossed 1m into the air initial velocity would be 4.4m/s
- cannonball weighs 19kg
- shrunken size would be about a marble, with a mass of ~2.7g
Initial momentum of the cannonball would be 83.6 kg·m/s. If momentum is conserved, the marble would travel 30963 m/s, or Mach 90. That’s unreasonable.
So for this to make any sense, conservation of momentum shouldn’t be preserved. In other words, mass would be added with the current velocity, so it would increase momentum as it unshrinks.
Bullets typically weigh between 20 and 40 grams. In addition, we can calculate kinetic energy as
KE = m * v^2, which means the velocity changes exponentially relative to the mass (I think I incorrectly assumed a linear relationship before).So in your thought experiment, the 19kg to, say, 19g transformation would change the velocity by a factor of 1000^0.5, or about 32. 32 * 4.4m/s = 140.8 m/s, which is totally reasonable (slower if the bullet is heavier, not sure about the density of a cannonball).
Momentum could still be conserved if the velocity is unchanged, but it would mean there’s now a lot of kickback once it gets big…
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