My story (set in the far future) has a bear-sized monster with a tough shell. The human settlers fighting it realize their ballistic firearms are not effective in killing it; though they may pierce the shell, the monster clots and regenerates tissue extremely quickly (like Wolverine’s “X-factor”). The urban environment takes explosives and chemical weapons off the table.

The humans put their thinking caps on and produce a five-foot-long serrated “harpoon,” designed to be impossible to regenerate from. The weapon is built from a magnetic, ductile alloy with a low melting point (suggestions are welcome).

The projectile is loaded into a portable, mounted railgun. The high output of the railgun superheats the projectile before it is fired from a short distance, impaling the monster. The spear point, malleable from the heat, twists on impact like a Roman pilum, so the monster can’t pull it back out, while the length and serration of the projectile prevents it from cleaving straight through the shell and leaving an empty wound to heal.

The projectile’s impact vibration, sustained by electric motors housed in its frame, prevent the wound from clotting. Even if the superheated “hook” misses any vital organs, the monster will quickly bleed to death, fry from the inside, or burn through calories trying to regenerate until it starves. The humans know very little about the monster’s biology, so the weapon is designed to kill in as many ways as possible.

Is this a feasible weapon? To be clear, the heat and vibration do not affect the cutting ability of the weapon; the railgun is easily powerful enough to pierce the shell.

  • $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – Monty Wild
    Commented Feb 25, 2022 at 0:52

10 Answers 10


It sounds like your people might be overthinking things and have come up with a complicated plan that is pretty much guaranteed to be a) hellishly expensive and b) not very effective. You'll need to dump a ton of heat into the blade, and that heat is going to bleed off very quickly once the blade is embedded. Surface heating from friction isn't going to heat up the core of the blade very well, and impact heating is really going to only affect the forward part of the blade.

Fortunately for your colonists there's a much simpler method that's been used for centuries back on Old Earth: harpoons. Put a big spear on a launcher of some sort (assuming you don't want to just walk up to the Doom Bear and poke it with a stick) with a good tough cable attached and launch it through some suitably tough spot on the beast. Unless the healing process magically ejects the barbed head of the 'poon or somehow eats through the shaft, you now have a handy leash. Add a few from different angles, tied off to solid anchors, and your Doom Bear isn't going anywhere. Oh, and man-portable harpoon guns are a thing, so depending on just how tough the beast's shell is you might be able to supplement your mounted launcher with a bunch of man-portable harpoon guns.

Not flashy enough? How about explosive harpoons? I know, it'll regenerate... but if you take out a big enough chunk all at once it'll either die straight up from hydrostatic shock turning everything inside the armor into a fine slurry, or at least be slowed down long enough to get some more boom on target.

Still want more? How about the classic anti-troll measure: kill it with fire. Not just boring old fire though, the slightly less boring napalm or even the fairly exciting white phosphorous round, let's replace the explosive in your harpoons with something that will really do the job: a half kg thermite charge with a magnesium igniter should do the trick. Not only will it char everything around the ignition point, it'll burn through the body cooking the thing from the inside out as it goes. And it's less toxic to the environment than phosphorous rounds, so bonus there.

Still not enough? Well, you're a hard customer to please. I know you said you didn't want to hit it with chemicals, but there's really only one go-to option once thermite has failed you: FOOF. A small amount of liquid FOOF at ~100 Kelvin in a (preferably very strong) capsule in the head of the harpoon, perhaps with a small explosive to ensure the capsule breaches on impact, and no more Doom Bear. I don't care how good your regeneration is, this stuff burns water. Enthusiastically. Then it sets the fire on fire.

Just... let me know when you're planning on making the stuff (no, I won't sell you any) so that I can be well out of town before you get started.

If your Doom Bear can regenerate from that then I'd give serious consideration to letting it have the damned planet. Or, you know, dust off and nuke it from orbit.

  • $\begingroup$ Better yet use a really big nonexplosive harpoon to transfix the monster into the ground. Then build an amusement park around the immobile monster and charge admission. Use ticket prices to periodically replace the harpoon with a slightly bigger one. $\endgroup$
    – Daron
    Commented Mar 4, 2022 at 15:38

So the settlers tried "ballistic firearms" which I take to be standard firearms using explosive propellants. Which then the following can then be considered as: do not use bulk high explosive or artillery.

"The urban environment takes explosives and chemical weapons off the table."

Small arms not big enough? Go next step up.

Use a 20mm vehicle mounted gun as weapons platform. A mix of incendiary rounds and explosive. The size keeps of round keeps the collateral damage lower then the monster damage. Incendiary would be white phosphorus. This would be next logical step up from rifles and hand guns.

High explosive rounds are very effective at destroying most targets if they are available. Certainly more available then rail guns. If 20mm is not good enough, go larger.

if a spear is really desired: KISS

Mostly steel construction. Narrow front wide back so that it will stick and stay. spring loaded blades for cutting. Saboted so that it can be fired from artillery. Have some Incendiary that is ignited on impact.

  • $\begingroup$ If .50 cal isn't effective (you've already broken my suspension of disbelief) then we move up to cannons, which is anything 20mm and larger, like the Vulcan in a Warthog, which usually have a mixture of armor-piercing, high-explosive, incendiary, tracer rounds, and everything in between and combinations thereof. If that doesn't put holes in it then you're handwaving. $\endgroup$
    – Mazura
    Commented Feb 25, 2022 at 20:24
  • $\begingroup$ @Mazura It’s not that a large round won’t damage it, it’s that the creature can repair itself and spit the round back out the entry wound (by magic if needed). Unless the round can blow the whole creature apart (as a Warthog probably would) it’s not overly effective. I can pretty easily handwave heavy autocannons out as options for a group of lightly-armed settlers, though. $\endgroup$
    – Mark Price
    Commented Mar 2, 2022 at 3:33

It seems too complicated

If the monster heals around the spear, then any old barbed spear ought to keep it tethered to a bolt in the ground while you build a big pottery kiln, blast furnace or fluidized bed coal reactor around it. Ideally the spear should be cast tungsten or something that can withstand the heat, but if not, make the observation portholes good and thick so you can wave every once in a while as it pounds miserably on the glass. Remember to make the Vulcan sign when you do, so it lives long and prospers.

  • $\begingroup$ Simple barbs won't stop the monster from pulling hard enough that it comes out. Doing a lot of damage on the way out because of the barbs / hooks, but unless it literally hooks around bones it's just tearing soft tissue which the monster knows will heal. It probably hurts a lot, but if the monster is angry, or intelligent enough to see the problem with being immobilized, it'll do it anyway. $\endgroup$ Commented Feb 25, 2022 at 6:56
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    $\begingroup$ @PeterCordes - depending on the monster this could be a fair criticism. The answer is more spears and more picadors to throw them. Each spear starts with a fairly long cable and distant anchor, but as the monster is distracted by the next thrower, the bold picador darts in to lock it down at a closer position. (Coliseum personnel on a level well beneath the grounds can bore upward to provide new attachment points where needed, without being injured) $\endgroup$ Commented Feb 25, 2022 at 14:49

I mean, there's definitely a way to make the spear work but using a system that involves...

  • A railgun
  • Advanced materials science (low temperature magnetic ductile alloy)
  • Electronics and moving parts inside the projectile
  • Some high-wattage instantaneous heating equipment

... is going to be extremely complex and expensive. You'd need a significant power supply to power the railgun and the pre-heater, and this, along with the general size of this thing, would make it an exclusively vehicle mounted weapon. Additionally, building electronics into a munition, is difficult, and adding moving parts that need to function after being fired is quite challenging.

If you really want to come up with a new weapon to specifically deal with this beast, maybe a large taser could do the trick: since you already have the immense electrical power supply needed for the railgun, you could simply use two railguns or traditional guns to launch two inert spikes that trail long wires into the beast. Upon hitting and penetrating, the monster heals around the spikes and isn't majorly affected, until the power is turned on along the cables. This fries the nervous system of the beast and while it doesn't kill it outright, it knocks it out and disables the regeneration (which is controlled by the nervous system). Once this is done, people can approach with power tools to manually take the incapacitated monster apart. That said...

Despite how "un-sexy" traditional firearms might be, they would still probably deal with such a monster quite well. I mean, small arms might not do the trick, but if you were able to mount a big weapon on a vehicle you could easily turn anything biological that the gun can be aimed at into fine paste post-haste.

For example, take the GAU-8 Avenger: a hydraulically-driven seven-barrel autocannon capable of firing 30mm explosive shells. Each shell, containing a depleted-uranium penetrator in the case of the armor-piercing variant, has the energy equivalent of around 50 grams of TNT. This is similar to the amount of high-explosive in a hand-grenade, so quite deadly but nothing obscene. Now consider that the cannon is capable of firing 3900 rounds per minute. No matter how fast the beast can regenerate, I don't think it would be able to survive this.

Man next to Goalkeeper CWIS

  • $\begingroup$ Small question, but I was hoping that a preheater wouldn’t be necessary, since the railgun’s firing generates so much heat in the barrel. Not sure if that’s realistic. A 30mm cannon would definitely work, assuming it’s relatively portable (or cheap to build lots of them), as the monster moves around quickly. $\endgroup$
    – Mark Price
    Commented Feb 24, 2022 at 10:44
  • 2
    $\begingroup$ Preheat also isn't necessary with chemical propellants. The round leaves the barrel hot, will be heated by friction with the air and with the monster's shell (Quora thread on impact temperatures). Pyrotechnics similar to tracer rounds can also ensure it's hot on impact. But you probably want an armour-piercing cap if the shell is hard and the round is meant to deform inside $\endgroup$
    – Chris H
    Commented Feb 24, 2022 at 13:53
  • 1
    $\begingroup$ "Once this is done, people can approach with power tools to manually take the incapacitated monster apart.” 😂🤣😂🤣😂🤣 $\endgroup$ Commented Feb 25, 2022 at 3:52
  • 1
    $\begingroup$ @EscapedLunatic I've already seen tasered and pickaxed slowly to death, but this is new level $\endgroup$ Commented Feb 26, 2022 at 9:27

A simpler alternative: make a serrated spear, with hinged barbs that protrude when it's being pulled towards the entry point. Have it attached to a cable and draw the spear in once the monster has been impaled.
Even if the regenerative powers prevent the beast from bleeding out, it is now captured, and can be beheaded or otherwise 'taken apart'.

  • Pros: no need for advanced tech, energy sources, or anticipating the regenerative powers.
  • Con: you need a powerful machine to power a heavy duty pulley. But it seems likely that's easy to accomplish in an urban environment.
  • 1
    $\begingroup$ Or harnessed for a cheap-ish source of mechanical energy $\endgroup$ Commented Feb 25, 2022 at 20:19

Just use incendiary rounds. Cauterized tissue would impede healing, and even if it can heal from wounds it would still die from its organs being cooked through (unless it completely ignores a lot of basic biology). Putting a couple of large White Phosphorus filled rounds into it would likely be enough for the internal steam pressure created by its blood boiling to make it explode, in addition to cooking its organs.


What you basically need is a cross between a board spear, an RPG and a rocket propelled immersion blender. In theory, you could get an immersion blender the size of an outboard motor but most of the components you need are there.

An RPG is a good start. It goes fast, and most of them are spin stabilised. Swap out the warhead with an inert stabby bit, and add something to keep it going right through like the tines on a boar spear and it'll penetrate just enough and stay there

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Now we need to blend. You could have small explosive propelled protrusions, or weighted balls with lines launching out... then... spin it. Heck maybe even deploy chains like a mineflail from the body of the weapon

Have a small set of rockets somewhere in the "shaft" that spins your entire projectile, kinda like a gyrojet causing massive damage from the spinning weighted wires. Maybe exhaust some hot gases into the body of the creature too for extra damage

So basically ... blend it from the inside.


Heated spear with internal electric motor vibrator fired from rail gun at close range in an urban environment...

Lets take each part of this idea, one by one

Heated - warmer materials almost always are weaker. If this monster shell has any armor, heating the spear will make it not penetrate the armor.

Electric motor - it requires cold material, below the curie point for magnetic core to work

Vibrator - requires a battery, and battery energy storage is much worse than an explosive.

Rail gun - designed to accelerate short projectiles. As projectile becomes longer, output speed reduces. Also it acceleration is extreme and will smash all the electronic and mechanic inside. Especially if it is hot.

Close range - railgun requires stupidly large power supply and rail itself is heavy. It is all so big that at close range even a hedgehog speed is enough to avoid it. It is too cumbersome to use railgun in close range. At whatever tech level, other uses will be preferred.

Urban - requires maneuverability for quick delivery, and more importantly cheap price to have thousands of ready installation all over the city for even quicker delivery time. Your contraption fails at both. Too slow. Too expensive to make thousands of it.

So, what would i change?

Use room temperature material for better strength and penetration.

Use short projectile for higher speed for more penetration and damage and cheaper weapon that can be made in many units and be easier to deliver.

Use no electronic or mechanic parts inside because they will be smashed by the firing acceleration.

Use explosive as energy storage rather than a battery, because explosive can do more work in total than a battery. Even if this work is cutting. If collateral damage is an issue, use low explosives like a gunpowder, that still rips stuff apart, also dont use cerrated metal shell to avoid shrapnel. So, a copper shell with low explosives, gunpowder that explodes after it is inside the monster. No collateral damage this way, not even windows will be damaged.

Use a short barrel with gunpowder prolellant for ease of maneuvers in urban environment, ease of movement so to not to carry 1000 tons power supply for a rail gun, because 1 ton gun will do just as well.

How to deal with regeneration? Just keep in mind that 1 kg of regenerated flesh needs 10 of of food. So to kill a monster you only need to turn 10% of it body mass to a mush. Thats exactly what modern weapon does. 1 shot of a rifle with 10g projectile turns about 1 kg of flesh into a red soup. Even better ratio for a sniper rifle, with many kg of flesh completely destroyed. A bear weighs about 1 ton, and 100 kg of his flesh needs to be destroyed for his regeneration to be irrelevant. Several shots of a sniper rifle will do the work. If a single shot is required, then anti aircraft guns have about the right amount of power. Tank shot is overkill, but will also do the work. Also aircraft and tank shells have an option to have explosives inside of them. Some minor changes to remove cerration and use softer metal for the shell to avoid shrapnel will help. For a single person a hand held rocket launcher will do the work. Especially the tandem shaped charge with a delay on the second stage. For first stage to open the armor of the beast, and second stage to enter deeper before exploding. Shaped charge armor penetrating ability is better than that of a railgun. And tandem shaped charge are nothing new today, and for sure will exist in the future as well.


Utility Fog

Gotta love utility fog. It’s useful. And you are in a far-future setting, so it is almost certainly available.

Utility fog, as proposed, is a large vat of tiny robots (a few millimeters across) that look roughly like barbed pollen. It was envisioned as made of aluminum, but could be made of something stronger. As I was saying, this stuff is robotic, and the barb like extensions are tiny arms that can telescope in and out, terminating in tiny hands that can catch the hand or arm of their neighboring utility fog node.

Despite the name, utility fog is in essence, the robotic metal from Terminator 2. The total amount of it doesn’t change, and it is always a semisolid bulk of metal (only appears liquid, never is), but the arms can telescope out to the point where the “fog” is nearly see through (like a force field). Or the arms can stay close, like a solid slab — or a solid spear.

Your bear-killing weapon could be a spear of utility fog programmed to expand into a tiny sharp fractal blossom. Since it has onboard intelligence, it can be programmed to recognize repairs being done by the monster’s regenerative ability, and grow a new spike to re-injure the part.


Frame Challenge

The urban environment takes explosives ... off the table.

ROTFL absolutely not.

  1. We use explosives All. The. Time. in urban environments.
  2. What are armored bears doing in you cities? Why aren't you hunting them(*) out in the wilderness where they live.

(*) using Really Big Machine Guns -- the M2 heavy machine gun should suffice -- that fire Things That Go Boom (HEI - High Explosive Incendiary rounds). And if the armor is really tough, step up to APHEI (Armor Piercing High Explosive Incendiary rounds). And if that doesn't work, as others have mentioned, you step up to 20mm or 30mm autocannon.


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