Forbidden magic options

Sex Magic
Blood Magic

Elemental magic. Not as in the four classical elements, but as in the periodic table. The moment you start animating the nitrogen in someone's lungs or transmute the iron in their blood to metallic cesium, shit's gonna go nuts and it's gonna get forbidden real fast. Not to mention turning shit to gold and crashing the economy.

Alternatively, any kind of magic that can cause hard paradoxes/errors in reality, like portal magic where you can make the portals intersect.

This is quite a good idea - and you could expand it further, perhaps the Church has a monopoly on weather magic, because only a god has the omniscience necessary to alter the weather without causing freak storms or droughts somewhere else?

Ostheomancy, the process of manipualting and mutating living tissues through magic. Can be either a seperate branch of magic or just the other side of the healing magic branch.

Make them a telemage. Mind reading, mind deceiving, mind controlling, everything they do has to do with the mind in way or another. You will be a walking nightmare, as not even the cunningest and cleverest of theives can hope to hide, for you read their minds like an open book.

Anything mind-controlling - depriving people of their free will has the potential to be massively taboo

Any magic that involves changing the shape of a living being, on the grounds that it a) is a perversion of the divine template that god/gods decreed each being should follow and/or b) it causes offspring of animals affected by such magic to be mutated. e.g. you cast polymorph on someone to temporarily turn them into a rat, later in life they have freaky rat babies

Any magic with the chaos descriptor - using such magics makes reality more and more unstable.

The D&D ones?
As I recall:
Conjuration/Divination = Alienism & Cerbrant practice, literally Bloodborne/Lovecraft mode

Illusion = Shadowmancy (not shadow weave)/Memeshit/Non euclidean geometry/Armchair alienism/Psychological horror Torture/That fucking Ravenloft Insanity doctors 3.5 spellbook/Night of Wallachia/Trumans World, and some dystopian future shit, Eteral Tsukuyomi

Evocation = Elemental Evils/Sole elemental Force Devotion/Blood Magic/Nightmare Magic/corrupted magic stuffs

Transmutation = Fleshcrafting/Thaumaturgy/Skincrafting/Grafting/Mutation/Fucked up template stacked horror creation/Literally Nyralathotep/Shoggoth mode

Necromancy is Necromancy.
Anyhow, you'd want to be a Wizard (nec) anyhow because Lichdom per Ravenloft allows you to get access to your forbidden spell schools after the transformation, speed reading, Power rituals salient abilities, based on INT score, Lichspells, Lich Artefacts and more to Demilichdom, and this is even better if you follow pic related. After that, you just get in on Alienism, find a cerebral blot and become a cerebrant, and now you've the power to throw people into a hellscape of non-euclidean gemotry and Epic-level TPK threats of the highest Dynamic disorder.

this, you can even tie it in with maybe some eldritch horror tentacle monster god.

Or hemomancy. Cause people to hemorrhage, or stop healing, heal yourself or allies with the life force of your enemies, or even make weapons from either your own blood or the blood of enemies (or in vials you carry around) like giant spears or some shit.

Can even take pages out of Bloodborne for inspiration and start to go crazy over BLUD.

Fire magic

He comes from a heavily forested (covering 90+% of the land mass) medieval world where most buildings are made from wood

Since slinging fireballs around could easily destroy a town or start a massive forest fire, there is a strong prohibition against fire magic

(and, for consistency, pretty much any use of fire - e.g. any cooking in a given town must be conducted in a centralised fire pit (with a massive water quench system) and anyone found with a cooking fire in their own home is given the death penalty)

How about anti-magic?

E.g. being able to generate a field around youself that shuts down all magic, or to anchor null-magic fields to a given place, etc.

Make the "forbidden" aspect be that they're from a

How about anti-magic? users being able to generate a field around themselves that shuts down all magic, or to anchor null-magic fields to a given place, etc.

Make the "forbidden" aspect be that they're from a magi-tech based civilisation (with pretty much everyone being magic users) where electricity never took off, so it's the equivalent of walking around with a phone jammer and/or EMP projector.

Not only does it jam spells from being cast, but interferes with any magi-tech in the area of effect - say you have a pacemaker that uses spells both to function and to make it surgically safe, then you walk into an anti-magic field and suddenly you have a lump of useless metal attached to your heart, which your body is now starting to reject. And you can't send a magical broadcast for help because of the field, so you're probably gonna die.

Or to cause larger scale problems, casting a null magic field on a magitech "power" plant and shutting down thaumic power transmission to an entire city. That kind of thing.

Carnomancy

The fuck even is carnomancy

I'm guessing meat magic

a joke from a webcomic, erfworld, used to be hosted on GitPG, the guy who writes OotS, the D&D comic with the stick figures.

Precise divination of the future. While postcognition and vague augury are acceptable and commonly practice, but magic that truly reveals the future is completely forbidden. The reason for this is that such divination doesn't merely reveal the future but sets it in stone, and not merely for the one prophisized over. Everyone even remotely related to the passage of the prophesy is ensnared by the threads of fate, bound to only one course which ensures that what has been seen will come to pass. Gods and demons, beggars and kings, all are bound by the doom revealed by the diviner.

Life magic that manipulates the germline or otherwise creates heritable traits is also forbidden, specifically because it tends to get out of hand really fast and have all kinds of terrible consequences the caster did nazi coming.

Shit they got him before he could tell us why they forbid antimagic

I fucked up and hit post by mistake, and then I thought I had deleted it but I hadn't and now it's too late to delete the post.

RIP my brain.

That's carnymancy

>Blood magic
>Commune with the dark gods
>Awakening the moon

There's always the not quite as fun option of certain practices being subjectively "wrong" based off of the most common cultural values.

Then there's pretty universally spooky options, like tampering directly with the energies of life or whatever soul concept exists in that universe. Maybe even bonus points for being heretical in a religious society for trying to Play God, reshaping the stuff of creation as such.

Do taboos and geas instead. If certain rules are broken, bad consequences ensue.

>eg. The feet of the caster must not touch the ground.

So, talking to children?

foot soles
fucc u JM

Blood magic
Sacrificial magic
Any magic that messes with the minds of others(especially charm and dominate-like effects)

One of the big taboos in my setting is blood magic. Any form of magic that requires you to drain life from a living creature is stepped on pretty hard because of bad historical incidents involving planar war, mass necromancy, etc.

One of the big things that every wizard tries to avoid mentioning is that's how all magic works. Modern practices just drain life only from the spellcaster (it grows back eventually).
Kind of like how the reason necromancy is so hard to extirpate is it's easy to derive from first principles if you know how healing magic works.

These are good ideas, genetic engineering has always been pretty spooky concept to me because of the aforementioned gradual unseen repercussions, like cursing a species from the past, I just don't trust people to meddle with it.

Something I always thought would be cool (which I've integrated into the campaign I'm currently running) is a specific counter to your "forging gold" issue. The gold produced is, in the most easily comprehensible spells, only of a Au195 due to the loss of the terminology to produce Au197, the only stable, and thus mostly naturally produced, isotope of gold. Because of this, less dense gold can be detected, though only when specifically looked for: a random tavern isn't going to have a gold-density calculating machine right there. Because of this, cities often weigh and volume the gold of anybody entering them (this is basically my way of telling players their accounting between trips, it's easier to say "a pile of gold in the chest" for example, and more realistic too). Oh yeah, and this type of gold is radioactive, so it generally doesn't flood the market.
One "problem" with this whole idea though: the isotope which Au195 decays into is Pt195, a stable isotope of platinum, which has its /own/ effects upon the world at large. Something of note though, this transmutation is only known in some areas of the world, culture shock, and in this case, technology shock, are a nice easy driver of major plot arcs.

I always had this idea that the more powerful the school of magic the higher the cost of casting is.

So my idea would be that any school of magic whose cost is far to high would be highly discouraged or outright forbidden.

Like imagine a type of magic where the caster is alowed to sacrifice portions of their own life span to buff the power of the spell. So a normal fireball that would burn a 20ft radius with a cost of a few years of life would blow up an entire building.

Then again this would also go for classic Wizards. I mean why would you waste an entire diamond every time you try to teach your apprentice. Compound that over years an apprentice would cost a shit tonne.