How can I prevent witches from cheating the magic system?

Question

Witches have the ability to siphon Mana from other individuals to add power to a spell. They accomplish this through specially designed runes, which are tattooed to an individual. This rune links the person to the witch, who can then draw Mana out through the metaphysical link. This method is not without its dangers however. Drawing out too much power can harm or even kill the subject. Therefore, safety standards have required that witches limit their siphoning to 40% of the person's Mana supply or less.

Evil witches naturally wouldn't care about safety, and would gladly sacrifice a victim for power. For more scrupulous witches however, this stipulation naturally blocks witches from accessing the most powerful spells, as they normally require more power than witches usually have. Research has developed a possible workaround. By placing runes on multiple sources, a witch can draw Mana from several individuals at a time. This can allow them to bypass this rule without potentially killing someone by using more than one person at a time, drawing up to 40% from each.

I would like to limit access to the most powerful spells to dark witches. Therefore, I need for this method of siphoning power from multiple sources to not be a viable alternative to the normal method. How can I prevent "good" witches from gaming the system ?

Answer 1

I want you to round up two people. They are going to sit 20 meters away from you, and they are going to do something random with their hands for 5 seconds. Your task is to tell what each individual hand was doing.

It's hard to concentrate on four things at once, isn't it? And without the option to learn from muscle memory or learn the pattern (as there is no pattern), it's going to be very hard to improve. Not impossible, but it's going to take an exceptional mind to really use this to great effect.

That is the limitation: you need to concentrate on the spell and each added individual. While one or two exceptional good witches might be able to use more than two or three individuals, most witches can't. On top of that, the risk of accidentally taking more than 40% and killing your subjects would increase.

Answer 2

Look at bone marrow transplant. One cannot simply take some bone marrow from the first walking by stranger and transplant it to a receiver and be sure that everything will go smoothly. The donor and the receiver have to accurately match in their characteristics.

Same can hold for your mana system. The witch and the individuals have to match, so that the fingerprints on the mana are very similar. The more complex the fingerprint system on the mana, the more difficult it is to find a matching donor and consequently the even more difficult is to find more matching donors.

Scarcity of matching donors also forces the witches to treat them well: you don't want to waste something which is rare.

Answer 3

I say... Make it HURT.

Not the witch, but the person being siphoned from. Make the mana source suffer EVERY time. After all, they're getting their magic power / mana / psychic energy / friggin SOUL cut out of them and ripped away... That's going to be painful and traumatic no matter who does it. Heck we need anesthesia for surgury IRL -- it's not like you have a mana-surgery anesthesia, right?

And make it ALWAYS potentially damaging and able to leave the source / willing donor with lasting side effects - psychological, physical, magical... sky's the limit with how you can torture your characters with it.

If this mana share is ALWAYS painful and ALWAYS potentially harmful thing, then it's going to be an inherently EVIL act. Good witches might have an entire congregation of willing sacrifices (cough SHEEP cough) to draw from, but a truly good witch will shy away from hurting other people and only do so as much as they need to... And when a good witch DOES take power from others, they'll be gradually making themselves more evil just by doing so. One day a good witch might wake up and realize, "Oh, wow. I sucked little pieces of soul out of someone enough times that putting another person in agony to achieve my own goals no longer bothers me... Guess I'm evil now. Neat."

You know... Using people is both evil and the path to evil.

And back to magic anesthesia... Only a truly EVIL EVIL wizard would have a tower cell filled with prisoners held in a magically induced coma just waiting to be fully used up when the time called for it. "You owe me money, peasant? Either become my willing sacrificial battery, or your wife and daughter get it." One by one the battery-room gets filled.

Anyway, just an idea.

Answer 4

Make it private

The connection established via the rune is something very intimate. Generally the connection is only built with people you are very close with. Consider it a bond like a relationship. Inviting another person into this bond is not only undesired by your current partner but also frowned upon by society.

Evil witches keep their bonded individuals like slaves, ignoring the intimacy of the connection. Also the social stigma of their other deeds makes the stigma of bonding multiple indiviuals look miniscule.

Answer 5

Finding Volunteers

If siphoning off a person's mana has the potential to kill them, then people are going to be reluctant to offer themselves up to a witch who wants to use their power - even for good reasons.

Sure, you might be able to pay a lot of people to volunteer for this, or coerce them in some other way, but you're still limited by that resource, be it money or whatever coercive method you're using - not to mention, the ethics behind such coercing.

And honestly, an evil witch wouldn't dare take too much mana from their own volunteers - or should I say, slaves. They would keep them alive as long as possible, and numerous as possible, in order to abuse them for their magical essence as often as they can. There are probably legal ramifications for this - but there would also be witches who can find loopholes in those laws and still keep a huge number of 'volunteers' for their power.

Answer 6

If I'm reading the question correctly, your specific problem seems to stem from the idea that you want good witches to be able to access these higher power/level spells if the occasion warrants it.

So instead of being able to use multiple sources, the obvious solution is to use multiple witches. Bad guys and gals are famous for not working well together, meaning they require the ruthless full drain methodology to access the top teir.

To make this more practical, you might want you to modify your percentages. Blood donation takes about 1/8 of your blood at a donation. Eight witches working together with their individual sources matching the power of the single witch draining a source entirely seems possible. At the 40% level you're only looking at a two/three person team up, which seems much more ad-hoc-able.

Answer 7

Witch hunters

What you have isn't a balancing issue, it's a law enforcement issue. Your solution should be an in world taboo or law enforcement system. The power spike is detected by the enforcement agents and they respond. Anyone using such a method is automatically flagged as "dark" by the rules of "good" simply as a result of the amount of power they're drawing.

Excessively heavy handed law enforcement for the few laws they're able to enforce always has a place in a world. Mary-Sue automatically gets flagged for her base power level because of this monitoring and the story begins.

Answer 8

Draining Mana is a exponential curve.

That first 40% is the tip of the iceberg. any further than that and you start drawing Mana out of the lifeforce of the person that comprises that majority of their personal Mana. This is high quality, dense, and basically requires killing your mana battery (oops, person) to acquire.

Witches for the most part can't externally measure the density of mana and thus find that the weaker 40% of an individuals mana is "free" mana without connection to basic bodily function. Dark witches have learned through performing the taboo that the real good mana sits deep inside the person.

Since Good Witches spells use the low density mana (and can use multiple people repeatedly) they can do pretty powerful spells without killing. However, A single Bad Witch can use the same spell and much more powerfully using the increased density while killing her battery.

Bonus, having high power is kind of like a high for most people. It would be hard or impossible to reform a witch who has touched that delicious high density mana as the 40% method would never allow them to reach that peak again.

Answer 9

The answer may be simple: cost.

If you siphon from more than one individual at a time you suffer a cost.

Aging

The easiest one should be aging.

Tainted

The other can be a kind of taint or marking of the witch. The more individuals you sample from, the more likely that you just aren't "normal." And since the multiple sources thing is traditionally the purview of "evil" This can be anything from freaky eyes to bat wings to extra fingers and so on.

You are getting very Sleepy

Although you can access powerful spells, the consequence of this is being really, really tired. So much so that you can pass out. Now, over time you can build up the ability to stay awake after these spells, but the more you access them, the more time over time you will be asleep.

Power backlash or Burn Out

With great power comes RISK. Think of the mage as a transformer/conduit of energy--or if you like a faucet. Only so much can come down the pipe/wire aka mage casting the spell. Too much pressure and the plumbing bursts or the wiring burns out. There's a risk that the magic can go wild, creating a disaster that normal people and good mages alike would like to avoid. It's no good funneling all that power to save the village when there is a possibility that funneling all that power may reduce you and the village to a smoking crater in the ground.

Answer 10

"Therefore, I need for this method of siphoning power from multiple sources to not be a viable alternative to the normal method."

You're the author, say "No".

There is no 'multiple sources' technique, if you don't want it.

If you need the 'multiple sources' technique to power a really bad Witch, then it's a secret (ie: don't give it to good Witches). Or something they can't use: first kill the victim's first-born child and bathe them in its blood...

One Witch, One Rune

Each Witch can only maintain a link to one rune (or only one rune at a time). Evil Witches can drain for 100pts (or 99pts), good Witches max out at 40pts.

Assuming that every person has a uniform level of mana. Maybe bad Witches have learnt to double victims mana by torturing them to death: 200pts available at time of death! Or found victims who have 150pts.

Could also take time/effort/cost to reset from one rune source to another (so killing your rune source is a problem, depending on rate of recharge). Or takes zero time/effort, but still only one link at a time: means good Witches get up to 40pt spells, but bad Witches up to 100pt spells, at all times - until they run out of rune'd victims.

Answer 11

Load balancing. It's difficult to control the sources in a group working on an individual basis. There's a high probability that, in drawing from a group, you will exhaust/kill some member of the group. Not a huge ethical concern if you're already evil, but if you're using the ethics, you need extreme care.

Answer 12

Upon rereading the question, I realize I've answered something slightly different - how to limit the multiple channeling to evil witches, rather than how to limit the strongest spells to evil witches. But if evil witches can pull off multiple channeling when good ones can't, that too limits the strongest spells to evil witches, so I think it still works as an answer.

The channeling process begins with a minuscule flow of power from the witch to the donor, and that flow persists while the channeling is ongoing - the witch's power forms the structure through which the donor's power flows. When the donor's power flows to the witch, their power mixes together and the structure is now made of the mixed energies.

When the witch is channeling multiple people at once, everyone's power mixes together and all links start to contain everyone's power. But normal, non-witch people react adversely to contact with another normal's power. The more people being channeled, the larger the power flow and the longer it lasts, the worse the health effects. Harm to her (probably unwilling) donors isn't something that much concerns the evil witch, but a good one would probably stay away from such practices unless absolutely necessary.

Answer 13

It’s not a mana faucet. It’s a mana Shop-Vac.

The mana doesn’t flow like water out of a faucet. If it did, the multiple runes theory would work great. Add more faucets, turn each tap up to 40%, enjoy mana.

It doesn’t work that way.

The mana doesn’t have any reason to flow on its own. It wants to stay where it’s at. A witch can pull the mana to herself, sure, but she’s acting like a mana Shop-Vac.

I’ve got a Shop-Vac in my garage. It is mounted to the wall. It has one hose. I turn the vacuum on, and dirt flies into the hose and up into the vacuum. Works great. So I should put a splitter on it and add a second hose, right? I could vacuum up twice the dirt! And why stop there? I could put lots of splitters on. I could have eight hoses all coming out of this vacuum. I’d be like a vacuum octopus. I could clean my whole garage in a second, right?

We all know this doesn’t work. The vacuum doesn’t have enough suction to deal with more hoses. You might get a slight breeze, but the dirt isn’t going to move at all. You’re just running up your electric bill and getting nothing to show for it.

Answer 14

You have a bigger problem : evil witches completely siphoning several victims. So, you have to take into account :

• access to spell
• number of living mana battery
• number of sacrifice

The access to spell only work if you have either a codified magic system, where draining magic is part of the spell casting (so if you cast a spell this way, it has this result) or if magic is somehow "moral". You can't do much with that.

For your other problems, I'd kill those birds with one stone : draining someone implies to create a link with that person.
The deeper you drain, the deeper the link.
Every one has a limited capacity to link with other people. On the other hand, each link takes approximately the same time. You can adjust by saying that voluntary link are faster than reluctant one.

So draining two people of 40% of their life essence will cost 80 "point of link". But will need to establish two connection. Draining one person of 80% of his life essence will cost 80 "point of link", kill the mana-battery. But it will need to establish only one connection.

So : every witches can cast for the same effects, but the evil one can do it quicker. If you take relationship or resistance from the sacrifice into account, good witches could be almost as efficient... and evil cult leader can be lightning fast. But not unlimited, as their total link capacity is limited like every one else.

Somehow, I'd link directly this capacity with the caster total life essence. The trick would be that you could drain yourself to death at most. But witches cheat by draining someone else. You can also adjust individual power by making it dependent on experience, talent, personal sacrifice...

Answer 15

Make it so that the witches needs tattoos as well.

Then you could build up on that, it could have cultural implications having to many tattoos, for example a witch with tattoos on her face would be seen as possibly evil etc. The tattoos could also grow according to the percentage of the mana they've siphoned or something like that. They could also be permanent, meaning a space is used up if they've killed someone.

That way you would create incentives for the good witches not to game the system and the evil witches can't just use the system without thinking about what they're doing.

Answer 16

Drawing mana from more than one source at a time requires concentration. Only the most skilled witches can draw mana from more than a hand full of people at a time. This restriction is independent from how much mana they draw, so dark witches have an advantage.

Answer 17

Evil witches would not want to kill their victims since 100% mana of dead people is considerably less than 40% of living ones. If the spell requires really big amounts of mana, witches are going to need several siphons they can drain upon for a long time.

So if you need several lasting links, limit the number of links an upright witch can use. The amount of mana you get out of the link is reduced by distance so if you want to get the whole 40% of several people, they need to be as close to one another as humanly possible - literally stack them up in cages and keep them there for hours. No decent human being would do that but it allows you to drain upon them as efficiently as possible, resulting in 40 people giving you as much mana as 400 people would if placed in a humane way.

Mix in pain for the drained ones to limit volunteers or a (less extreme) concentration limit as suggested by others and it is close to impossible that a decent witch can cast top tier magic.

Answer 18

I'm not sure if this fits with what you want to do with the story, but this is what I immediately thought:

Since these more powerful spells are performed by dark witches, perhaps the spells themselves could be "dark" spells. The spells require more than just enough mana, they also require a "spark of life" to be taken from the host. You actually have to kill, or nearly kill, at least one person to give the something extra that these powerful spells require.

This would obviously make this type of magic more explicitly dark/evil, instead of just a powerful magic that only rulebreaking witches could access. I'm not sure if that would be beneficial or detrimental to the world you want to make.

This would allow for a few options as well. For example, perhaps to actually allow the connection to take this spark of life, the rune would need to be specially designed to take something extra. The dark witches could hide this secret, even further preventing good witches from being able to use those spells. This could also allow some interesting scenarios where a good character figures this out, and has to decide if they want to sacrifice someone else to use these powerful spells.

Answer 19

The root of mana in an individual is powerful. Losing it means dissolution of the body.

Regular mana comes in different kinds. A body can regenerate it from an inexhaustible source, a seat of power which "can never be dispensed with" and which is integral to the organism.

The Serpent Power, Arthur Avalon, 1918

According to my presentation of the case, something — viz., a dynamio equivalent or ‘ operative double ’ — is certainly sent forth from the Muladhara, but this basic centre or seat is not depleted or rendered void of static energy in consequence of that operation. The Mula (root), as the seat of static or coiled power, can never be dispensed with. It is the sine qua non of all functions of the triple body (gross, subtle, causal). It is, so to say , the buffer or base against which any activity of the Jlva (embodied conscious- ness) must react or recoil, like a naval or any other kind of heavy gun against its base or emplacement. Thus while the dynamic or uncoiled Shakti ascends the axis, the static or coiled Shakti retains- its place at the Mula, and remains as the very possibility of the dynamic upheaval…

So far all can agree. But the question is : Is the Mala depleted or deprived of all power (espeoially coiled power) when that dynamical expression leaves it and ascends the axis ? Is the dynamic expression wholly at the expense of the static ground ? Should the latter cease in order that the former may commence ?

“ Here, I think, I must answer in the negative. It is a case of Power leaving as well as remaining — leaving as dynamic and remaining as static ; it is the case of the Kundall being uncoiled in one aspect or pole and remaining still coiled in another aspect or pole. A paradox, perhaps, but, like most paradoxes, it is likely to be true.

I have claimed throughout that the Muladhara, as the seat of static ( i.e ., coiled) power, can never be rendered a vacuum in relation to such power except in the circumstances of Videhamukti (bodiless liberation), when the triple body (gross, subtle, causal) must dissolve.

This source powers the strongest magic and taking it dissolves the triple body. Forcefully depleting a body of the Mala, or root, inflicts "bodiless liberation" on the individual. Of note, this is also a state which can be temporarily attained (with difficulty) by yogic energy manipulators, and which can be useful and helpful to them. Persons who are thrown into such a state by the depredations of an evil witch usually are not yogi masters and usually wind up as disempowered fragmented spirits. But not always.

Answer 20

Opening subsequent 'connections' is exponentially harder.

Using 0 donors allows the Witch to use 100% of their power. Every donor reduces the witch's available power by 5% (to maintain the conduit), but adds 40% of the donor's power. Connecting to the $N^{th}$ donor takes $3^{2N}$ seconds

From here, all calculations are made on the assumption that everyone has the same mana capacity - Witch or not.

Connecting to 1 'donor' ($Mana = 95\%^1 + 1*40\% = 135\%$) takes about 9 seconds
Connecting to the second 'donor' ($Mana = 95\%^2 + 2*40\% = 170\%$) takes another 1 minute, 35 seconds.
The third 'donor' ($Mana = 95\%^3 + 3*40\% = 197\%$) takes 12 minutes, 9 second more - total time 13 minutes, 39 seconds - and now you're about as powerful as an Evil Witch was after the first 9 seconds.

To be as powerful as a 90-second Evil Witch ($Victims = 2$ and $Mana = 95\%^2 + 2*100\% = 290\%$), would take between 5 and 6 'donors' ($Mana = 95\%^5 + 5*40\% = 277\%$ or $Mana = 95\%^6 + 6*40\% = 314\%$) and either 18½ hours or almost an entire week.

Give an "Evil Witch" that same week, and they'll be casting with $674\%$ of normal Mana. That allows for some pretty impressive spells - ones that would take you over 6 million years to match

Answer 21

There are way to constrain the most powerful spells for the dark and/or evil witches. Individual methods will solve individual issues and play on a different aspect of the world.

The Most Powerful Magicks Require a Sacrifice

If a spell requires the sacrifice of a sentient, then good witches are either going to be reluctant to do it or the assumption is that it will be their own sacrifice that powers these spells. This plays on the differences in morality beween the two variants of witches and allows for interesting moral situations.

It may not be necessary the sacrifice of a sentient either -- it just has to be a price that the average good witch is unwilling to pay in the normal course of events. Those that know of these magics will be burdened with the knowledge of them and their costs.

Should these sacrifices leave obvious evidence of their use, then the law-enforcement angle can come into play. These spells without permission from the local leadership is an immediate harsh sentence (likely death or immediate banishment). The trick is to come down hard and fast on those that utilize these sacrifices.

Just Because You Can Does Not Mean You Should

Others have touched on this, but the idea that the runes that bond magics together are the thing to limit. In general, spells do what they are designed to do. Once you deviate from that, then you get into unknown territory. Overall, this deals with the bonding magic itself and the mechanics that this runs off of

The core premise here is that these runes are designed to bind the magics of two beings together. The moment a third is added to the link, complications may ensue.

• As other answers have stated, concentration increases when more are added. This makes adding too many people to the link impractical past a world-defined point.

• When you pull mana from the link, it pulls from all people simultaneously. The pull stops for all parties once 40% is taken from any one single person as per the safety measures. So if your third person is weak magically, it might end up that the witch actually gains less from two people than they would from one.

• The safety measures built into the runes to prevent death by draining actually prevent magic being drained from more than one person at a time for any one spell. Whether this takes the form of not being able to place the runes on a second donor, or not being able to open a bond to a second person while the first is open is up to the magics. By contract, the hallmark of the dark withces are these runes without the safety measures in place.

• There are unknown complications when a witch applies the runes to two living beings. Unknown in the sense of they differ every time because of the three magical forces involved. They could theoretically range from actually beneficial to the death of all three participants. Because the side effects are not codified, this is considered a last-ditch effort for good witches

The Long Arm of the Law

If there is enough konwledge of amgic, then the ruling factions will have regulations as per its use. If the magic is powerful enough, then the punishments for using either banned magics or banned methods to using the magic will fit the crime. This plays into the morality of the witches but by creating consequences that loom over them should they step out of line.

It might mean that the bonding runes have to be a specific sequence to be legal, or that certain spells are banned outright. Regardless of what measures are taken, it needs to be demonstrated that the law enforcement has to be able to deal with the perpetrator.

Note that law enforcement does not necessarily have to be soldiers or police. It could be the witches themselves that govern their own actions.

Metagaming

An in-world response might be that witces in general do not consider bonding to multiple people. It might be a societal taboo, or one that is ingranied to them when they learn this spell. A good witch might actually know of this and consciously decides against it to prevent them being branded a dark witch. Regardless of the whys behind it, the key point is that there is nothing that explicitly stops a good witch magically speaking, but something that personally stops them.

In contrast, a dark witch not only knows of this but does this willingly. They accept the consequences of their action and exploit this for their own personal gain and profit.

Answer 22

You could make it that every persons mana output has its own fingerprint, and that mixing mana fingerprints makes it more likely to make a spell fail since it becomes increasingly volatile. Using more than two fingerprints on a spell almost always results in a complete fizzle of the incantation and leaves you without access to any magic for a length of time. That way you would leave room for a special someone to be able to channel multiple peoples magic at the same time without it being something just anyone could do.

Answer 23

Differing types of Mana

Much like people have different blood types, people have differing types of Mana. However, there area LOT more types of mana than blood types.

Almost all spells require singular type of mana, so even if you have several people rune-marked, you can probably only cast one spell at a time. Most witches can "convert" the mana to the type needed for a spell, but the process is lossy, especially the more different the mana is from the required type. It's also more difficult the more people you're drawing from.

So if they had two rune-marked people with very similar mana types it might be possible to get close to 40% + (40%/2)= 60% power. Meanwhile an unethical which can just straight draw 80% from one person much much easier.

Answer 24

Differentiate the capture methods...

You note that the law establishes that a witch can only draw 40% of the vict...I mean "volunteers'" life force. This prohibition would seem to be one of intent not power but if you determine that the method of capture is different for that slow siphon versus the hard and fast version you would keep all the variables in place (good witches limit themselves, bad witches take without care) and still maintain a power difference between the two.

Example: In order to slowly pull power the good witch has to create a looped feed. They draw power from the volunteer but have to backfeed lifeforce into the person to ensure they are only taking a certain amount. For every unit of power they pull they pump 40% back into the person. This takes careful planning, training, etc. and will be more difficult the more volunteers are added (juggling 2 balls = easy, juggling 15 is very difficult).

A bad witch will create a similar but subtly different connection with their volunteers. The bond is one way - no back feed. They can pull the energy fully from the individual without need to balance a return of energy. This would mean the bad witch can quickly and far more efficiently get energy for their spells while also allowing them to perform such magic with fewer volunteers.

The spells for the one way bond would be forbidden but would also allow you to set up moral conundrums, etc in case your good protagonist was required to perform some fantastic feat of magic quickly...

Answer 25

This rune links the person to the witch

...and as you know, a witch can only be bound to one person. The bond links the two souls, almost as one. Also, as you know, it's impossible for a witch to bind their rune onto more than one subject. Binding a second simply releases the first. One witch's soul can only be bound to one subject.

Stopping at nothing in pursuit of power, some witches have began experimenting. You may well be familiar with over drawing from the subject, it is one of the first things witches learn to not do. These more sinister witches ignore it. However, binding to another subject takes time and the raw power extracted is difficult to contain before it dissipates and the process of binding a witch's soul to a subject's takes time -- and becomes more difficult the more power you're holding on to, like trying to write while balancing more and more books on your head.

There is a tale of a witch who found a way to extract souls. Unfortunately they have no power without a body, but the bond persists. Naturally, the order of witches denies any such witch (or group) existing and forbids research into witches' souls. Because after all, if a witch could hold onto another witch's soul and keep that witch's subject alive, they would, in effect, have access to two subjects' power reserves. This would make them twice as strong as any one witch. And if they were already so power hungry as to murder one of their own, what's to stop them from continuing? And just how powerful could they become? No witch could ever defeat them alone. So, naturally, any research into this is forbidden and the existence of any such group is denied.

But I think we both know the truth.

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Basically, allow a witch to only be bound to one subject. However, allow the killing of other witches for their still bound souls allowing the "bad witch" to be more powerful.

An interesting thing is this would allow the "witch order" to be evil if you wanted it to be and instead have the "bad witches" just be traitors to the order instead of "evil".

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A small issue is that witches may just want to give their souls up other witches when they are nearing a natural death. Because of the cascading effect of a power hungry witch getting more witch souls, there could be extreme pressure from the order to not do this. Or maybe only a few of the elite members (maybe only the ones who know about the technique, since it makes sense to keep it secret) know of it and some have a few souls. This could even lead to a schism if the rest find out.

Answer 26

Building on the Idea of L.Dutch - Reinstate Monica:

Every donor has certain characteristics, a set of "parameters" which exactly define their mana composition. The witch can attune to the donor's characteristics, so she can use one donor at a time, regardless of their characteristics.

If you want to use two or more donors at the same time, they have to have matching characteristics, because the witch cannot attune to two different sets at the same time. Matching characteristics are very rare, a big city may have a few sets of pairs and that's it. Searching the whole country may give at best a group of five, but you first have to find them.

Another problem is, that each additional node in your donor network requires additional overhead, a (multiplicative) kind of tax that reduces the effective amount of mana you receive:

• 1 donor = 80%^0 * 1 * 40% = 40%
• 2 donors = 80%^1 * 2 * 40% = 64%
• 3 donors = 80%^2 * 3 * 40% = 76,8%
• 4 donors = 80%^3 * 4 * 40% = 81,92%
• 5 donors = 80%^4 * 5 * 40% = 81,92% (value will drop with 6+ donors)

Should you want a plot point, where the hero witch of the story can square against the dark witch, then she maybe finds a group of quintuplets with identical characteristics, resulting in the tax being more lenient with only 90% effectiveness instead of 80%, resulting in 90%^4 * 5 * 40% = 131,22%.

Answer 27

It's not too complicated. Make it simply that there is no way for one user to control where they're siphoning mana from. A spell is typically a manifestation of energy, where one force is concentrated into another force that then has an effect on another thing (eg: You concentrate power to create a ball of fire, then if thrown, it will damage whatever it hits).

How does that happen? Well, the witch concentrates her mana into the spell. If she's siphioning from others, she can also concentrate their mana into the spell. The key thing is, since the witch would typically be closer to the spell, the spell would absorb more mana from her rather than from others. In other words, if she draws enough mana (assuming everyone has a similar pool) to kill someone, she's likely dying too.

Furthermore, the very act of channeling mana from others IS using mana (you have to at very least "poke" something to start the reaction, thus, that would also have its own risks

Answer 28

Multiple runes means your sources are pooled - and the negative effects thereof.

In short, if you rune two people, their identities splash together: normally like smooth crystal clear pools, with a single tap being a gently flowing waterfall, having two creates a complex (and messy) interaction of minds, creating whirlpools, eddies, currents, etc. What was once a clear mind becomes cloudy and muddled. Although it could potentially create a positive effect in those mingled, the majority of the time it causes just noise which results in insanity.

Answer 29

There are many ways you, the writer, can go about changing this. The way I would personally go about it is to have the energy input to output ratio become heavily skewed. Let's say under normal circumstances the user inputs 10% of their energy to activate the runes which can then siphon up to 50% of the target's energy which ends up coming out to a 40% max energy surplus to fit with how much energy you want them to siphon. The exact numbers are irrelevant for now and can be changed to your liking.

Now, when you suddenly start activating multiple runes on multiple targets, not only are you inputting 10% of your own energy to each person, meaning a theoretical maximum of ten targets at once which may even result in death depending on how literal you take the energy drain idea but the actual practical result is that due to the strain and complexity involved when activating multiple runes at once, each individual link is weaker or not as highly optimised leading to a reduction in power efficiency. In the end, for two people it requires 25% energy input on your end for each rune to be activated, to gain 50% from them each so in total, your energy surplus is only 25% instead of 40% from each person resulting in a total net gain of 50% energy.

Compared to the one person method, you have now gained an extra 10% of energy output for you to use but at a vastly reduced level of efficiency and this is the optimal circumstance. Just as many may not be capable of draining 40% from an individual depending on their skill or power level, with each witch having varying degrees of efficiency, creating new runes and implementing new ideas to try and improve upon the input/output ratio, many who try multi-link runes end up expending more energy than they get out.

In the example above, even the best when drawing power from two people will only see a 10% increase in power, allowing for some cool moments in your story where they can gain extra power to pull off an ability but without it becoming entirely broken within the narrative you wish to tell.

Then when you go to three people, you may be inputting 40% energy to activate each rune which either can't be done as you go over 100% of your own energy and possibly die or become injured or in cases where it can be done by perhaps activating one rune and draining energy from them which is then used towards draining energy from another three, even then, you end up with 30% output from those three people for you to use which is actually worse than if you had just siphoned one person to the max.

In Conclusion: The more people you choose to siphon from simultaneously, the more energy you need to begin with meaning you must first drain others individually to accumulate the power necessary making it long winded and time consuming but you also increase the complexity and introduce efficiency issues which makes it generally unviable. The exact percentages are of course entirely adaptable to suit what you feel is right within the story, possible allowing up to four or five to be siphoned before you end up with a net loss of energy. That's just up to you.

The only final thing I would add, is that remember, if the witches can drain life from humans and they restrict themselves to drawing that 40% out of an ethical or moral code, they are most likely able to draw life from trees, plants and animals too. In which case, depending on the witches in your story and how they view these things, those codes of ethics may not apply. However perhaps this is not possible within your system and energy can for whatever reason, only be acquired through draining people.

Answer 30

In a comment on your question, user @Hearth mentions The Runelords.
You could borrow an idea from there: chaining ("vectoring").

A witch empress in the distant past discovered a way to siphon mana from witches themselves!
While regularly only peasants are siphoned, this dark technique allowed siphoning magic users - at great difficulty.
This allowed the Dark Empress to take not 40% of a person's mana, but 40% of a buffed mana user - in effect getting a 96% (= 1.4*1.4) boost!

The Dark Empress explored this dynamic to siphon from a long chain of witches, getting unheard amounts of power.
She used a chain of a dozen enslaved witches, having the magic strength of 50 people. (5669.4 %)
Her power was unchallengeable. The legends say she defeated an army of the mightiest witches without effort.
It was many years before the secret was discovered and the Dark Empress was betrayed by a greedy general.

This chain-siphoning has become the darkest of sins.
Several times in history, others have tried to use this power; the results are always catastrophic! Society and culture have shifted and developed an innate panic of chaining.
Any such dark practice will cause mass panic and a globalized Jihad soon forms.

Because the method for the Unforgivable Horror is known, it is a matter of time before one of the links is found and the chain is cut.
Once the Dark Witch loses a large fraction of their chain with such a cut, they're no longer an unbeatable dark hero but just an overpowered caster, and a dedicated group will soon take them out.