There are characters in my world who have magic blood that they frequently need to shed for various reasons, including but not limited to - during combat to try to get it on their enemies for some spells, across rooms to lay traps, etc.

Note that volume of blood doesn't matter too much, rather, what the blood touches or what it is near is more important.

However, they still need to be able to fight. They need to be able to draw blood easily and accessibly (say, with a knife, a sharp stone, or if nothing else is available through biting. That would cause a bit too much bodily damage though). And the blood flow should be able to be staunched a short while later, giving enough time to shed the blood and spray it or arrange it or whatever, but not enough time that sever blood loss is caused. Moreover, though regular cutting and damaging would of course leave a scar, no more than superficial permanent damage can be tolerated.

Do note that these blood people have increased blood regeneration and also wound-healing powers. However, the wound healing can only be stretched to a limit and aren't too far above normal humans.

Is there a practical place for these people to reliably cut to draw blood with all the conditions true, or will more handwaving be needed?

  • $\begingroup$ Does the advanced healing factor also affect the likelihood of scars and infections? They are likely to be big issues. Also: should we assume pain isn’t an issue here? $\endgroup$
    – Joe Bloggs
    Commented Jan 15, 2021 at 6:37
  • $\begingroup$ They do have stronger immune systems because they are sort of "built for this". As for scars and pain, neither are an issue. No one cares if their body has many scars when they are fighting for the lives of millions. Similarly, the burden of their task, as well as conditioning since childhood gives them a higher pain tolerance and better willpower to, for example, make cuts across their body at a moment's notice when in the middle of a fight $\endgroup$ Commented Jan 15, 2021 at 6:41
  • $\begingroup$ You state that the volume of blood doesn't matter, but then also that they need to spray it. It seems contradictory. $\endgroup$
    – L.Dutch
    Commented Jan 15, 2021 at 6:53
  • $\begingroup$ I mean volume of blood is more of an indirect requirement. A few drops smeared over a small surface area will have similar effect to more blood over that SAME AREA. Volume comes into play when you do need more quantity of it - such as if they need to spray it across a distance. I was talking about the effect of the blood, not the 'deployment'. $\endgroup$ Commented Jan 15, 2021 at 6:58
  • $\begingroup$ If blood is spraying from a wound, it will be fatal without stopping it somehow (first aid, medical attention, etc.) $\endgroup$
    – NomadMaker
    Commented Jan 15, 2021 at 17:00

4 Answers 4


There are certain people who need to frequently draw blood for medical purposes. What to they use?

A device that with a needle punctures their finger, so that the drop of blood can be used for the test.

diabetes test finger puncture

The puncture doesn't prevent the punctured from doing any other activity, apart from the short time it takes from the coagulation to stop the bleeding.

  • $\begingroup$ Just a single drop is still too little. Would you be able to draw as much blood as needed to cover a sufficiently large surface? Also, as you talked about in the comments, they sometimes DO need larger volumes $\endgroup$ Commented Jan 15, 2021 at 7:48

If scars are no issue the scalp and shins both bleed consistently when cut but pose no risk of serious blood loss as the skin is so shallow. If you need lots of blood just keep knocking the new-forming scabs off. If you need it to stop then slap a bandage on it.

Another (awful) option is deliberately scraping something down the inside of the nose. This would liberate a lot of blood in a relatively controlled manner, but it’s much riskier than the other two options because it’s much harder to staunch afterwards, and could lead to serious issues if it goes on too long (not to mention... ow...)


A cut on the tongue:

Depending on the location and depth, a cut tongue can bleed a lot or very little as needed.

It is conveniently located inside a container (the mouth) that can gather the blood over time, and hold it ready for application.

Same container is already linked with muscle and air structures that can direct the blood as a slow stream, or a shortrange spout, or a medium range spat globbet, or a shortrange aerosolized spray.

Same container come pre-supplied with cutting tools to initiate the cut, for emergency situations where a better tool is not available or time is of the essence.

It seems blood is something really, really potent in this universe, one does not want it to just spill where the enemy can get to it. The mouth also come pre-supplied with the means to keep the blood sealed in, and even to dispose of excess by swallowing if needed, preventing the misuse of this valuable tool.

Lastly, even in normal humans, the tongue heals incredibly quickly. A 1cm deep cut can be closed and nonbleeding within 30 minutes, and all trace of discomfort gone within 2 days, in a healthy individual. With an improved healing factor these people should be able to do even better!


Radial artery stick.

Artery stick


The radial artery is handy. It is under high pressure, so sticking it with a needle will produce a jet at arterial pressure thru the needle. Blood can go some distance. The artery is muscular and once the needle is withdrawn it will clamp down on itself and stop bleeding. You can do this over and over. It hurts but magic is a harsh mistress.

If you want more blood faster you could stick the femoral artery with a larger gauge needle. There is serious blood in there there and it is even more muscular. You might need to wear a Gstring under a skirt to allow fast access to your femoral artery. Oh good, you already are.

Do not cut the artery. Do not cut the artery. Stick the artery with a hollow needle. Do not cut the artery.

  • $\begingroup$ The bit about the hollow needles is really helpful. Thanks. $\endgroup$ Commented Jan 16, 2021 at 13:03

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