Spells that would be effective against a modern day army but would NOT destroy a fantasy one [closed]

Question

I'm developing a story about a few hundred modern day US Marines who are transported to a fantasy world and must do battle with an army of Orcs and dragons. I know they will be extremely effective at this (see: literally thousands of other questions). However, to keep things from being too easy on them I'm gonna use magic to even the odds a bit.

In the world they are taken to, wizards play an important role in combat, but are NOT so over powered that it becomes pointless to raise huge armies of knights and peasants. Therefore, I need to come up with spells and types of magic that would be useful against my few-hundred marines, but would NOT utterly destroy a standard fantasy army of knights, spearmen, orcs, dragons, and eagle-riding elves.

A few I've come up with:

• Stun/Disable all troops in an area: stunning or disabling a few dozen spearmen would be powerful in a fantasy battle, but not necessarily decisive. However, with the marines relying on a small number of elite troops with massive firepower, disabling most of them for a short time could be quite powerful.
• Interfere with visibility: Clouding the battlefield such that visibility is vastly reduced would be useful in a medieval-style battle, but would not prevent a melee army from being effective. However, by preventing the Marines from aiming it could completely disable their primary advantage.
• Controlling/Possessing: Being able to possess a single knight or dragon is good, but not all that OP. Being able to possess the gunner of an M1 Abrams tank could prove far more disastrous.

Can people think of any other spells that might prove effective here?

Answer 1

Lead into gold

The good news is that the change made the lead parts of the bullets half their volume (20% smaller in every dimension), so nothing shoots right anymore and the guns love to jam. (Lead is 11.34 g/cc or 18.25 cc/mole, and gold is denser at 19.3 g/cc or 10.21 cc/mole).

The bad news, is the Marines have a fortune and can simply hire local mercenaries :)

Answer 2

An easy one would be an area of effect spell that negates combustion within the zone of effect. This would cause firearms to stop working and almost all vehicles would be unable to run. They would be virtually defenceless.

Another good one is a creating a localized EMP (electromagnetic pulse) to knock out enemy electronics and equipment.

With those two spells alone you could decimate a modern armies land,naval and air superiority,cut off the majority of communications instantly,likely cripple morale and leave them unable to defend themselves adequately.

If you wanted you could also use animate object spells on vehicles. Then suddenly your vehicles are all essentially enemy drone units that need to be destroyed by your own forces. In a medieval era such a spell is dubiously useful in warfare,but the era of mechanized warfare would change that.

Hope you found these suggestions helpful.

Answer 3

Rangar Lalazar was a third rate sorcerer from a rural backwater in the early first century. He is mainly mentioned in your first year magic textbooks for his invention of the "water to oil" transmutation spell. It is a good first level transmutation spell that is easy to learn, is emminently useful (for replenishing lamps during late night study sessions) and has very few ways to go wrong. The most notable of which merely causes nearby surfaces to become slippery. However few now remember that he also contributed this spell's opposite to our magical lexicon. So when our scouts reported that the strange metal beasts of our enemies appear to consume oil I directed our wizards to ambush them in the mountains with the "oil to water" transmutation and as they say, the rest is history.

Answer 4

Your question has multiple angles that have to been considered. We not only need a magical way of dealing with our modern tech, but we need a reason for this spell to exist before the modern tech existed, and we need this method to not be overly effective against typical medieval combat.

One idea would for there to be magic for dealing with specific large threats: I'm talking about dragons.

Dragons use fire as a primary weapon. Marines use explosives, which utilize fire, as a primary weapon. A spell to nullify fire in an area would be very useful against a dragon, but nigh-useless against even a peasant with a pitchfork. This spell would also have the side effect of rendering gunfire, rockets, and other similar modern weapons useless.

Dragons fly. Marines might have helicopters or other aircraft. A spell to ground flying targets would be very useful against dragons and helicopters alike. It would be useless against a ground army.

Dragons move very fast. Bullets, missiles, mortars, ATVs, Humvees, Tanks, etc also move very fast. A spell to impose a speed limit on an area would be highly effective against a dragon. It would be devastating to marines. It would have little to no effect on pike-men marching across a field. It might help, to a limited extent, against archers (although the higher mass of arrows would maintain effectiveness even at lower speeds... and arrows go much slower than bullets and missiles anyway).

For the sake of your story, I'd let these kinds of spells be somewhat esoteric. They're not useful on a day to day basis, or for most common threats of the world. A given wizard might know ONE of these spells, and that's all they'd need to aid their local knights in taking down the rare draconic threat. This would mean that your marines will have to adapt their tactics and methods based on which anti-dragon spell your local wizard is familiar with at the time.

Answer 5

Animate Dead

Bullets are not as effective on the dead as swords or axes. If someone falls in the fantasy army, they get back up and keep going. If someone falls in the modern army, they attack the soldiers around then causing fear and dread.

Answer 6

Enormous fireballs

"But wait!" I hear you cry. "Fireballs work just as well on medieval armies as they do on modern ones!"

Ah, but you see, magic becomes much more difficult to control at a distance. And fireballs are generally best utilized some ways away from yourself. But when cast from a sufficiently safe distance, even the most powerful fireball is trivial to disrupt for even the most junior of apprentices.

Mages are a critical part of any war effort. But big flashy spells are generally too easy to disrupt to be worth the effort. Unless for some reason you found yourself face to face with an opponent who did not possess any mages... Then it might be time to dust off the more dramatic part of your repertoire.

And don't forget the subtle stuff either.

Knowing is half the battle, and an unshielded foe is easily scried upon. Magical mist can conceal sleep spells and enemy attacks if there are no wind mages to blow it away. Familiars can get into all sorts of trouble against foes who don't know to kill them on sight.

And there are other threats, too

Gremlins are easy to discourage with salt and rowan smoke. It would be a shame if this foreign army didn't know to protect their highly complicated and breakable machinery with such measures.

Dragons generally refuse to get involved with human wars. But these giant metal beasts that throw fire are an insult, and these flying metal machines are even worse. No dragon could ever let that stand.

And I know not to get on the back of that nice horse by the river, and you know not to get on the back of that horse, but do these strange invaders know to be wary of this poor, innocent horse (who is totally not a kelpie, why would you even say such a thing)?

Answer 7

"Return to Sender" - a simple magic spell that reverses the velocity of incoming projectiles in the vicinity while it is being cast.

For the fantasy army:

• Swords, spears, clubs, et cetera are all unaffected
• Archers move after firing, so that returned arrows do not hit them
• Siege weapons such as trebuchets rely on drag to slow the projectiles as they arc through the air, meaning they "fall short" on the return
• Eagle-riding elves drop bundles of darts from a lower altitude than they fly at. Even if these are returned, just they go straight up and then fall back towards their original targets

For the modern army:

• Bullets fly straight back at the gun
• So do tank shells
• Grenades are 'fun' for the whole squad, unless you "cook it" to explode before it can be returned

Get your KA-Bars out

Answer 8

Definitely the EMP is a good idea. Would have zero effect on a medieval army but would decimate a modern one.

Depending on how primitive your army is, a magnetic spell could also be effective. Metal guns, bullets, tanks and electronics would be affected, but an army with stone spears and wooden shields would be fine.

Depending on the how advanced the modern army is there are some technologies that could render them useless. If the modern army uses purely combat drones then a spell could act like a jammer and block signals to the drones so they couldn't receive instructions or communicate. If there are drones or projectiles that rely purely on thermal imaging, a spell could disguise the thermal signatures of the warriors making them invisible and untargetable.

Could also go with a sort of bioweapon. If the advanced army is from a futuristic, sterile environment, the primitive army could have a savage virus that they've grown immunity to but the advanced army would be vulnerable to.

Things like summoning a flock of birds to fly into the engines of a fighter jet would work well too!

Answer 9

Instead of only considering the magic, consider the abilities of a fantasy army. They exist in that world, so they would be accustomed and trained to resist magic.

For example a fantasy army knows that when a confusion type spell is cast, they only need to counter it by thinking about someone they love (or some such mental control). Modern army? They all start shooting each other and foaming at the mouth.

Likewise, a fantasy army is likely to be issued gear with magical protections. Runes, trinkets, charms. These would make magic slide off of them, making them hard to deal with. Modern army? Sitting ducks.

Answer 10

When you have a modern army and remove the personnel, what you are left is a mile of intricate mechanics. So let us attack that.

Firearms have quite a few parts that need to move along. And move along freely. It would be such a shame if a sandstorm of finest sand would happen. Effect on humans ? Itching. On guns? You now have a few weirdly shaped clubs.

Or why not attack the movement a little bit more? If you can turn the oils and grease in the weapons into glue or something much less slippery, give it a few rounds and you are back at the weird maces.

Another fun thing about iron is that it's characteristic changes with temperature. And also it's thermal capacity is a tenth of that of water. So if you can just remove, lets say 16000J from each kg of material, humans will be chilly, at round 33 deg. Not comfortable, but alive. Iron on the other hand just lunged good 40 deg down. So maybe -20 deg? At that temperature iron is quite brittle. Swords are fine. It's a bulk of metal so it will not shatter. Easily. But the cute little things like springs ? And all the fine mechanics of engines and aircraft? Oh and also the rifle tubing ? It is unprobable that it would explode into your face, but possible and the chance that such a radical change of temperature would wreak havoc is really high.

Answer 11

How about an illusion or visual distortion spell which makes everything appear to be 1 degree away from its actual location? Against melee attacks and ranged attacks at short range (say less than say 10 meters) it has little effect. But it would make most longer range shots miss. Your marines wouldn't be helpless, but their effectiveness would be greatly reduced.

In the same vein, some sort of "heat" illusion might make night vision equipment useless, but wouldn't impede people with dark-adjusted unaided eyes.

Answer 12

Magnetic ball

Usually considered as more of a nuisance than real threat, as knocking out of hands a few dozen weapons usually does not cause much harm... except that such messing up with magnetic field should also cause EMP.

Raise dead: skeletons

Lowly vulnerable to piercing weapons, highly vulnerable to bludgeoning weapons. (Negates most of modern weapons advantages, except maybe ramming them with armoured vehicle)

Anti-arrow shield

The faster the object, the more effective it gets.

Bow, crossbow - 30-100m/s

M16 - 990m/s

Answer 13

Heat metal: Does wonders to modern weaponry and ammunition.

Same with lightning bolts and fireballs: Simple, but very effective and educative. You could even have a wizard zap a tank with a lightning and learn Faraday's cage effect!

Other options include invisibility, plain attrition (letting marines run out of supplies such as ammunition), horror type spells and mind control.

Also, things that would hinder medieval army would certainly hinder marines as well. If you can turn battlefield into a swamp or rations to rot, you're already halfway to victory.

Answer 14

I'm surprised no one has mentioned Divination and/or scrying.

These schools of magic would be extremely useful to know what opposing armies are doing on the battle field. Enemy supply lines, troop movement, and even things like morale are all laid bare to you through a bowl of water.

On the command side it would be like having a spy in their command center with out all the hassle of actually getting a spy in there. Access codes and other juicy secrets are just exposed for the taking.

Usually in fantasy scrying requires a piece of material from whoever you're going to scry upon. But this is war, if the rules of scrying are a bit lax, every bullet fired at you is a potential scrying reference. Push back the enemies? I'm sure there are plenty of small personal effects where they had been; playing cards, cleaning tools, ripped clothing, etc.

Fantasy armies would likely be less affected by these spells simply by virtue of understanding magic or having their own mages to counter the effect.

Scrying and Divination are all about knowing what your enemy is doing; and as GI-Joe taught us "Knowing is half the battle" (the other half is violence, and there are plenty of spells that already to that very well).

Answer 15

Summoning massive amounts of... controlable bats, crows or anything similar.

• Perfect for blocking vision - a solid, flying heat source, can crawl into places like tank visors, IR based nightvision etc. would also be ineffective.
• Can attack people who only have light uniforms on them - ineffective against armored knights or thick-skinned orcs or dragons.
• Can cause a lot of chaos. Imagine a thousand bats flying around.
• Make them echolocate using radar frequencies.
• Small and fast - guns would be rather ineffective. Flamethrower? Thousands of BURNING bats flying around - even worse if you don't have fire protection on yourself like a plate armor.

Answer 16

Anti-Explosion Field

A spell which creates a field where any kind of explosion or combustion simply doesn't work.
Normal wizards use this spell to counter Fireballs from enemy wizards but they found it surprisingly useful to combat marines.

Bullets are propelled from the gun cannon by the reaction of a tiny explosion inside the chamber, usually with gunpowder. An anti-explosion field would turn weapons useless.

Protection from Tiny Objects

This spell was made with the intention to defend wizards from enemy arrows, but the arrows were too big and so the spell couldn't stop them. Bullets, on the other hand, are very tiny but fast things.

Turbulence

A spell used to move arrows and change their direction by creating a powerful turbulent wind around the caster. Swords are too heavy to be moved by the wind, but bullets no. The wind has enough strength to just deviate the bullets in a harmless way.

Answer 17

The animate dead answer had some good points, but why not go all the way and do a Follow The Bouncing Ball?

Rules cheesing aside, even a single marine suddenly completely losing it and hosing down his own people is bad enough, but even worse than the friendly fire casualties would be the morale loss -- especially if you're positing that the modern army has no effective anti-magical countermeasures.

Meanwhile, a peasant army would have a few dozen people affected (assuming they have lower will saves per average than your highly trained and disciplined marines) but peasants with melee weapons can't inflict anywhere near that kind of friendly casualties in short order -- plus, if wizards are a known factor, then this would be something they know might happen, so the morale shock is less.

THAT SAID, if there's one thing marines are good at, it's adapting fast when it turns out that Intel dropped the ball and Charlie's about to dance the Foxtrot, so even if they don't manage to obtain any magical assets themselves (hiring, kidnapping or stealing some if necessary) they should figure out the basics reasonably quickly, so don't expect a given trick to work on them more than, oh, twice...

Answer 18

Drain batteries

Render all lasers, radios, vehicles, and computers useless

Answer 19

A very large slow zone

This kind of spell would reduce the speed of a medieval army. Strong, but no big deal. However, all modern systems are based on reactions happening at extremely precise moments, through precise speeds ; so even a minor disturbance of the physics speed would break most modern systems.

Answer 20

Since the modern army equipment works on some kind of redox reaction, what you need is probably a spell capable of triggering that reaction and dissipating energy (maybe against the enemy army as heat). This should work with

• Thermal combustion engines
• Black powder
• Fuel-Cells
• Common batteries

A medioeval army, being equipped with swords, spears and elastic-energy weapons (crossbows and bows) will not be affected by this "Dispel Redox" spell.

Answer 21

A complex and very hard to cast spell, that makes all gunpowder in an area suddenly combust.

A marine scout spots mages doing this complicated spell and start yelling for his troops to throw their guns away. In a couple moments, bullets start ricocheting all around, rifles break in half and grenades cause a massive explosion in the middle of the battle scene.