"magic system that works on the basis of" lemme just stop you right there. did you know the most important parts of the steam engine & heat exchanger as technologies were invented by people whose internal concept of thermodynamics was literally backwards to ours
the only “fleshed out” magic system I really like is Tamsyn Muir’s in her locked tomb system. everything else should just be answered with a big-ass shrug and an “I CAST SHIT YOURSELF”
“There’s a big heart in a big underground castle that pumps out our universe and pumps in another universe and that’s why for some reason I can make laser beams and eat people with my brain” is all you need. Literally anything more creative than “Wizards have magic übermensch blood”
I want, if I ever run a DnD game again, for magic to be a scientifically understood system but with debate about specifics, and no one knows what miracles are or how to make wild magic happen in a laboratory setting
caloric and phlogiston are a remarkably coherent system for understanding a lot of things about the world but break down under closer observation. humans are not incurious but also not omniscient, not even scientifically modern ones
arguably many of the most important parts of nuclear physics - as in the physics of nucleons - were only particularly clear even to specialists long after the point at which humanity as a species was using implosion lenses to turn lumps of plutonium into hell bombs
a system where wizards throw lightning bolts and lack any particular system for understanding them is incorrect. there should be more lightning wizards who incorrectly believe they can resurrect the dead if they cast lightning good enough
your characters should in the general case know less than you about the world they live in. i can't imagine they could know more and if they know exactly as much as you do, it becomes very boring very quick
sometimes experiments yield unexpected results which never meet with a satisfactory explanation in the lifetime of those who perform it. if your corpse explosion spell depends intimately on blood type, good luck to a necromancer who doesn't even know about red blood cells figuring it out
i don't think all such necromancers would be satisfied by simply saying "it works sometimes and doesn't work others". maybe superstitions develop, or maybe a completely incorrect systematization becomes part of the occupational folklore. who knows. way more interesting that way
type O necromancer who's corpse explosion spell only works on the same blood type slowly learns they can get consistent results on enemies who their blood splattered onto, multi-classes berserker instead of learning the secret
the royal family holds up their immunity to necromantic attacks as proof of divine favor but it turns out to just be inbreeding
Magic system based on thermodynamics but most people learning magic think there's a precise hierarchy of demons you summon to cause magic effects and their system of true names and bindings works 67% of the time because the summoning ritual creates a pocket of equilibrium completely by accident
"I have to intricately lay out the rules of my world's magic system and explain it practically." There are like ten different explanations for how heavier-than-air flight works and none of them are completely correct.