In this world there is a species of Apex predators that roams every corner of the planet, creatures basically unkillable... Oh, and it flies, very fast. But they have only one weakness, they are blind and almost completely deaf.

Instead they rely on a very powerful sense of smell that is extremely specialized I to detecting blood (like a shark on steroids), and it can do so from many miles away.

But monstrous creature aside, humans will human, and intraspecific conflict will develop. The only question is, how can war and weaponry develop in a world where spilling blood means calling death incarnate in a matter of minutes?

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    $\begingroup$ Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Worldbuilding Meta, or in Worldbuilding Chat. Comments continuing discussion may be removed. $\endgroup$
    – L.Dutch
    Commented Mar 28 at 18:21
  • $\begingroup$ Needs more focus? Less focus... answer is a single word : bludgeon. transitive verb 1: to hit with heavy impact | was bludgeoned to death merriam-webster.com/dictionary/bludgeon $\endgroup$
    – Mazura
    Commented Mar 29 at 1:25
  • $\begingroup$ Flying fast while being blind and deaf sounds like a recipe for crashing into things. $\endgroup$ Commented Mar 30 at 2:12

12 Answers 12


This is a Frame Challenge

Humans are the apex predator. Our problem-solving abilities ensure that. And I'm not a fan of apparently godlike creatures/characters, which means "unkillable" really suggests "in need of creative solutions." Why do I say this? Because there's nothing like a common enemy to make antagonists friendly. There are other consequences, too.

  • Your humans must be vegan because not a single drop of butchered blood can be had. If the tech level is high enough to seal the butchering process to ensure the smell never leaves the facility, then you probably have a high enough tech level to hunt and kill the creature with predictable success.

  • Your humans in the course of daily events must be the most peaceful people in the world because it sounds like a paper cut would bring doom to an entire city. Cutting yourself while fixing your car or working with sheet metal would be disastrous. In fact, the only tech level your humans can really be are pre-stone-age zen-Buddhists because the moment anything can be cut — from dinner to your lip — everybody dies.

  • In fact, your world has no other carnivores of any kind. It's a world of peaceful herbivores which the humans are required to mimic.

In short, it's a pretty boring world. Until humans get sick and tired of having an outside force tell them what to do. The question is, just how godlikeunkillable is your creature?

  1. If they have explosives, sneak up on the nest while the critter is asleep and set an explosive off.

  2. If they have rocketry, send the explosive from a distance. Preferably a tactical nuke.

  3. Poison the food supply. Slaughter a water buffalo then soak it in poison.

  4. Get into the aerial game with weighted nets. Lure the critter over water, net it, and let it drown.

What's my point?

There is no believable creature that's so powerful that human ingenuity can't kill it — and the humans would go out of their way to be sure the whole species is dead and buried before they start really laying into one another. Either that or they'd turn hunting it into a sport.

What weapons would develop? Poison and assassination until the real problem is solved.

Or, alternatively, the humans become masters at setting off bombs in the midst of their enemies from a distance so the bleeding masses of their enemies become the target of the beasts. Nothing like weaponizing Mother Nature.

  • $\begingroup$ Comments have been moved to chat; please do not continue the discussion here. Before posting a comment below this one, please review the purposes of comments. Comments that do not request clarification or suggest improvements usually belong as an answer, on Worldbuilding Meta, or in Worldbuilding Chat. Comments continuing discussion may be removed. $\endgroup$
    – L.Dutch
    Commented Mar 29 at 18:46

how can war and weaponry develop in a world where spilling blood means calling death incarnate in a matter of minutes?

By spilling metric tons of blood.

The problem is not "not spilling blood". It's not spilling enough blood.

Everybody bathes in blood, the city walls are covered in blood, and sentries shoot blood balloons at the sight of the predators.

If they smell blood everywhere, the blind, deaf monsters can eat blood-soaked dirt for all the humans care.

Once the monsters land to feed on a blood-soaked scarecrow, they are entrapped, starved, killed, their blood harvested, and squirted everywhere. Chemists learn to synthesize blood fragrances.

They are nigh-invincible.

Lure them into a blood soaked tunnel that slopes down. drop rocks. Not dead? more rocks.

Better, they fly at Mach what? They are just overgrown Willie E. Coyote on wings and steroids, who fly into a cliff wall painted with blood. Even if they are harder than rock, they are now stuck inside the mountain. Problem solved.

Bonus points if they paint a train tunnel on the cliff, with blood.

This "apex predator" is so dumb people would make a sport of luring them into the most stupid places.

Like your enemies' homes. I see the potential for a good comedy story.

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    $\begingroup$ Or they die the moment they cut open a pig. But them eating dirt sounds incredibly funny. $\endgroup$ Commented Mar 27 at 14:31

The invention of water-pistols saves the day.

You should should draw blood and place it in the pistol (with a basic anti-clotting agent eg. a ferment of sweet clover, or mosquito extract if you have the patience). Carry with you at all times.

If you get cut, squirt the first creature to find you in the face (if that's where they keep their noses) - this will blind it sense of smell effectively making it unable to track you.

It has the added bonus of attracting other creatures to the smell, squirt them too. They will tear each other to pieces. (If they're realy stupid, they'll tear themselves to pieces).


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    $\begingroup$ ... I do not have the patience. I couldn't even imagine having the patience. I will recommend anyone who has that amount of patience for the title of "next buddha" (that's how that works, right?) $\endgroup$
    – Syndic
    Commented Mar 27 at 12:52
  • $\begingroup$ Hmmm but the water pistols leave water residue on them. That's going to be a problem if there are other creatures around, which apparently there always are. $\endgroup$
    – DKNguyen
    Commented Mar 28 at 1:46

The winning army is the one that would be able to leverage this apex predator the most effectively

Biological Weapons

In our world we have the likes of anthrax, plague, etc. that have been weaponized. In your world - if the arrival of these creatures is a guaranteed kill, the goal would be to find a way to leverage them to do all the hard work.

  • Ranged Blood Grenades

You use a launcher (either a catapult, trebuchet or for more modern times an explosive based one) that launches a blood bag with a small explosive charge towards the enemy - they get sprayed with blood, the creatures arrive, tear the enemy to shreds, victory.

  • Flechette type munitions

Think shrapnel/nail bombs - all you need to do is get one of your enemies to bleed and then they show up etc.

  • Blood mines/punji sticks

Area denial - this is even more insidious, unlike conventional mines which go 'Bang' all you need is a sealed container that ruptures when stepped on - which could be practically silent - then they show up etc.

  • Self-Sealing clothing

You didn't mention tech level, but if it's modern (and I'm presuming it is, since you talked about kinetic weaponry) - then having a battledress with some form of compressed liquid that seals on contact with air - so that if someone gets hit and would bleed (there's a small delay between the skin being penetrated and blood coming out) their suit would release these chemicals to try and stop the bleeding or at least stop the smell of blood getting out.

There's all sorts you could play with - think Dune and the use of the thumper - you want to call the predators to do your dirty work.

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    $\begingroup$ @Fallenspacerock - I mean probably would... But look at say the history of Nitro Glycerine production - we didn't stop making it because of accidents. The Manhattan project kept going despite the Demon Core incident. Early cannons used to explode etc. Yet we kept using these weapons because they are extremely effective. $\endgroup$ Commented Mar 27 at 9:19
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    $\begingroup$ I feel like people make too big a deal of the Demon Core. The two incidents killed two people. 54 people died building the facilities to purify the nuclear material, from plain ol' construction accidents. Two is kind of a drop in the bucket. $\endgroup$
    – jdunlop
    Commented Mar 27 at 9:45
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    $\begingroup$ @jdunlop - Fair points - but then on the flipside - people of that era took construction accidents as a given/cost of doing business. Point is - dangerous weapons, even ones dangerous to your own side (Gas in WW1) are seldom abandoned because they are so. Often the rational is 'if it's this bad for us, it must be worse for them' $\endgroup$ Commented Mar 27 at 9:57
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    $\begingroup$ @Fallenspacerock I mean, only if you take "blood bag" to mean an actual bag with blood in it. A low-tech, biological alternative would be to simply load a trebuchet with a pig (or other convenient animal) - sealed outside, check. Blood inside, check. Bursts open on impact, check. Just sedate it first or something so it doesn't struggle and start bleeding on your trebuchet. $\endgroup$
    – Syndic
    Commented Mar 27 at 13:17
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    $\begingroup$ @Fallenspacerock "There aren't going to be survivors or victors in this god forsaken world anyways! Let's take them with us! Launch the pig! Or it'll be you on that trebuchet!" $\endgroup$
    – DKNguyen
    Commented Mar 28 at 2:12

Humans would need to either wipe out these creature, live in a place the creatures cannot reach ( underground caverns with entrances too small for the predator?).Or learn to cover the smell of blood.

Bleeding in childbirth has already been mentioned. Also children bleed as they lose their milk teeth and women of child bearing age bleed regularly unless they are pregnant. Also accidents are impossible to completely rule out, no matter how careful you are.

  • $\begingroup$ +1 Thank you for posting this. I'd say a fair number of participants in this question discussion here could use a lesson in basic biology... $\endgroup$
    – fgysin
    Commented Apr 2 at 9:59

I believe these apex predators had no chance against us. We work organizedly, we can build traps, we can trick them. We would learn their behavior, their real skills and we would live on ways where they can not do anything.

For example, very likely they could not enter even a stone age house or cavern, if it was blocked by spiked objects.

We would use a bounded, bleeding, crying goat to cheat them and then we would kill them with bows.

But, most importantly: We could explain to each other, what these predator can do and what they can not; we could even pass this knowledge to our children. These predators had only their instincts and genetical memory, and thus they only had only a single chance against us.

The reality is that the stone age humanity would hunt them and eat them all very quickly. We, humans, are the only real apex predator on the Earth since we have traps, lances and fire. That is some tens of thousand years ago.

I think you must give them some intelligence. Without intelligence, they have no chance against us.

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    $\begingroup$ Unless they are more like mice. That's pretty much what Xenomorphs are: fast breeding and capable of living hidden amongst human dwellings. But then they would need to somehow not cause ecological collapse, which xenomorphs always do. Green, environmentally sustainable xenomorphs. $\endgroup$
    – DKNguyen
    Commented Mar 27 at 21:47
  • $\begingroup$ @DKNguyen Sci-fi xenomorphes don't die from hunger, predators in real ecology do. Being a predator already needs a lot of energy, afaik no predator can multiply like mice. $\endgroup$
    – Gray Sheep
    Commented Mar 27 at 22:44

It depends on the setting but! The solution is to kill off 'death incarnate'

The key issue: A lot depends on the technological level of the human societies in your world and how they got there. If we're talking about neolithic cultures that developed alongside your creatures? There would be a strong evolutionary drive towards non-violence given the high risks involved in warfare and the relatively low population densities (and also vegetarianism BTW).

If on the other hand the human cultures of your world were relatively advanced say bronze age and were somehow transported to the world where these creatures existed (or the other way around)? That's a different story. Then you have war like cultures that have to adapt to new circumstances.

Regardless however of differences in religion race or political creed on your world the single unifying necessity from humanities perspective would be eliminating this apex species from the face of the planet. It's what humans do, what we've always done.

If it wants to eat us? We kill it. If it's edible? We eat it. If its useful in some other way and can't domesticate it? We skin it for leather, boil it for oil or bake it's bones to make our bread etc etc. Cave bears, woolly mammoths, whales? It doesn't matter. So FRAME CHALLENGE: We're the monsters in the dark! And your creatures need to fear us!

To begin with all humans societies on your world would watch, observe and learn about the creature. Their strengths, weaknesses and habits. And once they know those strengths, weaknesses and habits?

Option one - start setting traps. Stake an animal/s out in a field in a trap and spill its blood. Then wait for one or more of the creatures to land, spring that trap and rinse and repeat - endlessly, until you run out of flying monsters to kill.

Option two - find it's nests or lairs, wait for the parent or parents to leave and kill the offspring. If one parent always stays put? Send for more hunters and wait until it's alone. Then kill them all (quickly) and run.

Option three - if it has specific or preferred breeding sites? Go there outside of breeding season and make them unusable to the creatures.

Option four - poison. Experiment and find out what kills it. Then as per the trap scenario lay down a poisoned baits.

Option five - kill the parents and domestic the babies. If we can think of a use for them.


Lower Technology Level

  • Bludgeoning Weapons: The most straight forward ones.

    1. If you want to avoid opening wounds you just have to break someones bones to kill them.

    2. These weapons would come various sizes but all would be used to break important bones like the spine for example.

    3. These weapons would also be devoid of any sharp edges and probably use a softer material to avoid opening a wound.

  • Wound sealing Weapons:

    1. These weapons are designed like our normal weapons but use something to quickly seal up the wound to not cause any blood loss.

    2. These weapons would work like stabbing weapons do in our world only they are additionally tipped to quickly seal the caused wound.

    3. These weapons would probably need trained individuals to effectively use them. And bringing multiple ones to the battle field would be a good tactic other if you don't want to reprepare your weapon during battle.

  • Ranged Weapons:

    1. The most difficult to use probably. Bows effectively work with piercing so we can't use them. Also s blut projectile would likely be to heavy to us.

    2. What may work are slingshots or maybe later on crossbows. As they are more capable of launching blunt projectiles.

    3. The projectiles them selves would be something like smooth rocks or something similar. Best would probably be hard rubber to not accidentally pierce the skin but i don't know if it commercially available in this period. Also these weapons require a lot more skill to use as killing someone is now a lot harder.

  • Early WMD

    1. Really difficult as there is not a lot that does not cause blood loss. But i have still some ideas.

    2. The best options are likely all heat based weapons like boiling liquids or similar stuff. Though it is questionable commercially available all of that is. Ohh and if you want to be really cruel burning everything works really well.

Higher Technology Level

  • Rubber Guns:

    1. Guns would likely be used to cause internal injuries and not pierce the skin of your enemy .

    2. These guns would probably be air powered or a similar weaker propellant. This is not is too avoid piercing the skin.

  • Electronic Weapons:

    1. While they are not really that useful in reality in 5his world they could be. As they can basically bypass a lot of armor if you don't put on a full on rubber suit.

    2. Likely they would work by piercing or just plopping an electrode on your enemy. After that you just send a high amount of electricity into your opponent.

  • Armor:

    1. Likely a lot more useful than in reality. This because most weapons i discussed are generally less deadly to begin with.

    2. In such a manner you'd see a lot more close combat. Also because generally speaking the weapons introduced lack range. This could maybe lead to every soldier just packing an extra close combat weapon.

    3. In this world it's generally harder to kill someone in amor. Which will lead to a lot of different changes like maybe knights on the modern battlefield. And i don't want to even begin with armored vehicles and such.

  • WMD:

    1. With modern technology we have a lot more options available. Ofcourse we can now just launch missiles on our enemy and watch from a save distance as the beasts destroy them. But we do have other options.

    2. Likely gas based weapons would be very common starting with things like tear gas or sleeping gas. Which is you want to be evil could end up with mustard gas and other bad chemicals.

Blood as WMD

  • The elephant in the room: Many people mentioned already that blood is basically an WMD in this world. I mean you can simply cut a person in one settlement and wipe it off the map.

  • Extinction Level Danger: Let's be honest here the aforementioned tactic us probably going to be used very often. This us just how humans operate. Combine this with the fact that simply having a nose bleed is disastrous well... Humans will probably not survive nor any other big animal for that matter.

Blocking out the smell

  • Protecting Settlements: To avoid such apocalyptic incidents as mentioned above humans have to come up with a solution. This would probably entail producing a smell that blocks the beasts senses or makes them want to avoid a certain area.

  • Dried Herbs as an solution: Likely after many incidents they would find some smell the beasts hate. This would probably protect settlements from someone just cutting themselves in the finger and dooming every one. And also stop people freely wiping out your settlements. Also people would generally take these herbs with them where ever they go. For a compromise we could just say these herbs block out small bloodless but you still need to avoid whole groups from bleeding or the beasts come and eat everyone.

The fate of the creatures

  • Hunting the beasts: No matter how invincible they seem there are always those that would attack these creatures. And maybe one day someone successfully wounds one. Essentially what i am getting at is that people would learn more and more about these creatures and eventually find a way to kill one.

  • End of an Era: As technology advances these beasts would become less and less of a threat. It would not be to long before humanity decides it has enough of living under the beasts tyranny. We can assume by the way what happened to European wolf's that these creatures would be hunted and as their danger is without any real world counterparts you can assume that it would be with an unprecedented malice. So these creatures won't stick around being helpless to fight back against the now better equipped humans as they slowly destroy them. So unless your beasts can extremely fast self replicate or tank a nuke to the face they will be driven to extinction.

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    $\begingroup$ While I agree with the other answers, I appreciate that this one tried to actually answer the question as written. To the list I'd add "melee poison" weapons - rags on sticks soaked in hydrofluoric acid or chloroform or organic mercury or whatever, try to hit your opponent in the face (or maybe hit them with a blunt contact-poison arrow from a distance). $\endgroup$
    – Erhannis
    Commented Mar 29 at 7:49
  • $\begingroup$ @Erhannis thank you. While i taught of poison darts and the likes i was unsure as they pierce the skin. And i already had a lot of stuff omn this. But yes poisonous weapons are also something very useful in this world. $\endgroup$ Commented Mar 29 at 8:31

Check out the premise of Brandon Sanderson's novella Shadows for Silence in the Forests of Hell. The Simple Rules of this world are

  • Do not kindle a flame.
  • Do not shed the blood of another.
  • Do not run during the night.

or you will attract an attack of deadly Shades. These shades are possible to fight only with silver, and the rules can be broken in fortified, silver-lined settlements, but breaking them out in the woods is a death sentence. Rest assured there is still lots of killing in this novella, with poison, traps, etc. as well as other cool adaptions such as chemoluminescence.


Frame challenge

Completely bloodless warfare, or even life, is impossible. Just falling down can summon the beasts if you break your nose or scrape your knee. Others have pointed out that humans are going to find a weakness and start setting death traps eventually. However, exterminating an entire species takes time, and, as you pointed out, humans will human. If your neighbors kidnapped your children today, you're not going to wait a couple decades for the monster threat to die down.

The first priority for people in this world will be fortifying their settlements against the beasts. If they can't do that, they will die. There are other questions on this site on how people can protect themselves from a flying threat, so I won't go into details here. Caves or bunkers would be obvious choices.

The second priority will be protecting themselves when they go out. If they can't do that, they will die the moment they get so much as a nosebleed. This could mean armor, or armored vehicles, or simple scent bombs.

The simplest and most obvious weapon in this world is the beasts themselves. Warfare will focus on breaking through your foe's defenses and summoning the beasts with a well placed blood bomb. Capturing and training them as war animals will be valuable, if you can do it.

If you want to attack someone without indiscriminate slaughter, (for example, the kidnapping neighbors who still have your children) then the first step will be to set off scent bombs to cover the smell of the inevitable bloodshed. Depending on tech levels, there are different weapons that can reduce the amount of blood spilled. Clubs and other blunt weapons are simple, but you need to go for the head if you want to put someone down quickly, and head wounds are bloody. Nets can be used to entangle and immobilize your opponents. On the higher tech side, you have things like less-lethal tasers and extremely lethal flamethrowers.

Addendum: killing the beasts

"Basically unkillable" just means "killable with enough effort", and the threat they pose will ensure that people will be willing to pour a lot of effort into killing these things. The fact that they will attack anything bleeding makes them very easy to trap.

Do they need food to live? Lure them into a cage and leave them to starve. If they're particularly strong, the "cage" can be a pit with a heavy stone ready to seal the entrance. Do they need to breathe air? Set up drowning traps or gas chambers. Can they eat sharp objects safely? No? Fill bait with nails and broken glass; a time-tested method that is simple, cruel, and effective. If they can survive a razor-blade meal, what about grenades? Do their nervous systems rely on electric pulses? Set up electrified nets and electrocute them, and if that's not enough to kill them outright, drop the stunned animals into a trap that will. If they are so voracious that they attack each other, then you can splash them with blood and let them rip each other apart. You can lure them into a kill zone and set off high explosives or poison gas. And so on.

If they can learn to avoid death traps, even better, that means that they can be taught that human settlements are death traps, and should be avoided.

  • $\begingroup$ There's an Eskimo trick to killing polar bears - take a sharp, flexible fish bone, bend it tightly and put it in a blob of fat. Feed the fat to the polar bear (which generally swallowed it whole). As the fat melted/digested, the bone uncoiled and killed the polar bear from internal injuries. $\endgroup$
    – DWKraus
    Commented Mar 28 at 12:11
  • $\begingroup$ @DWKraus I think I'm gonna chalk that one up as "hella apocryphal". I can find one reference from 1917, which doesn't go into any more detail than you did and cites no source, and wasn't likely written by someone who would have seen it in person or spoken to anyone who had done it. $\endgroup$ Commented Mar 28 at 18:30
  • $\begingroup$ I read a short story in grade school some 47 years ago about it, and it was so clever that it stuck all this time. $\endgroup$
    – DWKraus
    Commented Mar 29 at 0:47

If the problem here is that causing someone or something to bleed invites further conflict, then we deal with these beasts the same way we deal with bees.

Bees also get triggered when they smell death. Everyone who knows about this and has to deal with bees uses gases (poisonous or not) to get rid of them.

Likewise, in order to hunt without fighting for the spoils, our ancestoes would use less sharp things and more... whatever is not sharp. They would learn to break a deer's legs with stones inside a leather bag to keep it from running, then roasting the beast alive.

Later on, when agriculture becomes a thing, you murder your lunch by suffocation or drowning, rather than the classical cuts to the neck and feet.

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    $\begingroup$ But then how do you eat your lunch? Swallow it whole? $\endgroup$
    – DKNguyen
    Commented Mar 28 at 0:01
  • $\begingroup$ Oh wait. You could just cook it whole. Surely that does something to the blood. $\endgroup$
    – DKNguyen
    Commented Mar 28 at 1:45
  • $\begingroup$ @DKNguyen cooking preserves the blood somewhat, but deep frying or burning the carcass black turns that blood into something else. $\endgroup$ Commented Mar 28 at 4:41
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    $\begingroup$ Cooking denatures the blood though. Do the predators still chase after that? $\endgroup$
    – DKNguyen
    Commented Mar 28 at 4:43
  • $\begingroup$ @DKNguyen good question, but only OP can answer $\endgroup$ Commented Mar 28 at 12:12

In such a world, there would be creatures that eat carrion- without spilling blood. Either by sealing the entrance hole while they feed- or by injecting the young into the dead or dying carcass. They also would eat fast, due to stench of death attracting the ulti-predator and they have to launch from the lunchsite to escape becoming wiggling snacks.

Now if we assume we have a bunch of fast eating and duplicating, eggses and we load them into a projectile not to dissimilar to the foam darts of nerf guns and fire them at a victim, leaving behind only a red dot when pulled off.

Then the feeding frenzy sets in, they shut off the motor functions first, fearing you could scratch yourself- but the pain receptors still work. Beneath your skin, one becomes many, you can see them ripple, you can feel them coming up- and then what was you is eaten, while your screams die- because your airways were sealed up.


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