Shrug. "I can understand that fire and gravity can be two categories such that magic might be able to pick one but not the other, but it's harder to intuit how gravity and flight can be different enough unless it's a raw power limitation?"

"No, raw power limitations just affect mana cost. The difference here is that elementalists can give themselves magic, and that magic can likewise only affect themselves or actual, like, things made of matter. An elementalist can't get power over electromagnetism or gravity but they can get better vision or magnetic senses or gravity senses or what-have-you. So flight is a power they get that affects themselves, and elementalism is a power they get over matter."

"Okay, I can see the," he waves, "underlying rules, I think. Can elementalists do mental things? Besides senses since those sort of count. Or have radioactive-themed blessings? Mess with time?"

"Elementalists can do mental things on themselves, yeah—memory, cognitive boosts, stuff like that—but what's 'radioactive' mean?"

"If I understand correctly... matter is made of tiny tiny bits held together by a force similar to gravity and sometimes when that force is broken dangerous energy is liberated."

"And... that energy's, er, 'radioactive'?"

"Yes. It is just called radioactivity, and radioactive is the adjective."

"How tiny are we talking, here? And what's it do? Is it just—does it make stuff attract other stuff, like gravity?"

"Absurdly, counter-intuitive, how-can-things-even-be-that-small tiny. Not sure the exact measurement, but I think you can't like, use light to see it because at that point light is too big. And depends how much radioactivity is liberated, but it can produce a lot of heat and make areas very toxic to life."

"—oh, like the poison rocks people found?"

"It might just be that, actually. They aren't poisonous in the traditional sense, I don't think."

"They're not magical, either, I checked, so probably that."

"How did you check?" he says alarmed. "Or, how far away did you check? Because the effect can be really subtle and slow acting."

"Pretty close, but after they realised what it was they used magic healing so I'm pretty sure I'm not poisoned."

He is relieved. "Good, I think to protect against radioactivity you need lead or a a lot of matter between it and you."

"Mmhm. Anyway, that's elementalists. Enchanters can make magical artefacts. They basically define the effect they want an object to have—and that's pretty much anything from a warm blanket to a golem, there are even legends of sapient golems—and pour mana into the object while going through the definition in their heads. They don't have a maximum amount of mana, it just continuously charges from the moment they're born, forever. Artefacts have a mana charge that runs down with time and needs to be periodically recharged."

"And any Enchanter can recharge it? If it reaches zero is the artifact is forever lost or does it just need a new charge? What counts as an object here? Could you make artefact ink and give people magical tattoos?"

"Yeah, any enchanter can recharge an artefact, and if if it runs out it just needs a new charge. There's a little problem here in that it's impossible sans metamancy to figure out that an object's an artefact and if an enchanter tries charging a nonmagical object thinking it's an artefact it will become one. Anything inanimate counts as an object; plants are more difficult but count, too; animals don't. Magical tattoos are totally a thing, people from Bezanab in particular like having those."

"Oooh, can enchanted plants pass the enchantment to their offspring?"

"More or less. Plant artefacts shed some mana when they produce seeds or what-have-you, and that mana is usually consumed before the new plants are grown enough to be of use. So, like, 'yes,' modulo an enchanter being willing to spend the necessary time and mana tending for multiple plants."

"Cool, we have magic that can do that, but let's talk about your system first. What is next?"

"Arcanism. They also have infinite mana, like enchanters, but they attach magic to symbols rather than objects or themselves. Words count as symbols, as well as gestures, or drawings or whatever—any action that conveys meaning. They also have to come up with a definition and when they've done that and attached it to a set of actions, whenever they perform those actions and have enough mana they will cast the spell no matter what. Spells are either instantaneous—like, I have one that makes me change biological sex—or temporary—a common one is a flight spell. When an arcanist attaches a spell to something it's stuck with that forever, so they should be careful with it. They can also create scrolls with spells they made, and other people can use those scrolls, but they're one use only, and are destroyed when they're used."

"Nice, sounds a bit like sorcery rituals. Do arcanists have some sense of which actions are attached to spells or do they have to remember that normally? Is there any restriction to what symbols they have to use?"

"They have to remember it normally, and if they forget it can happen that they cast a spell accidentally. There are various techniques developed to prevent that, and mana cost is also related to how short or common a string of symbols is. I'm not sure what kind of restriction you have in mind, but a priori no."

"The restrictions I had in mind were if you could attach arbitrary words to spells, like flight could be activated by 'stay in the ground forever' or 'delicious swamp rain'. Or if spells have to share symbols if they are too similar."