The foundational concept of this world is that all magic has something wrong with it.
That is to say: for any of the four basic types of magic, there is a different reason why users of that type of magic are generally viewed with suspicion, and that reason always has a substantial basis in fact; the magic is genuinely hazardous to users or those around them, and although it's possible to mitigate that hazard, people have historically not done that nearly enough and so the magic has gained an unpleasant reputation which encourages people to only use it if they're the sort of person who doesn't mind picking up an unpleasant reputation in search of power.
The four basic types of magic are these:
Sun: Its elemental associations are fire and life. Its energy position is heat/light. Its thematic resonance is creation. Its corporeal focus is soul. Its living avatars are angels; its revenants are demons. The stereotypical Sun user is passionate and volatile; the outcome people tend to fear from them is mind control.
Moon: Its elemental association is water. Its energy position is cold/light. Its thematic resonance is transformation. Its corporeal focus is blood. Its living avatars are shifters; its revenants are vampires. The stereotypical Moon user is flighty and mercurial; the outcome people tend to fear from them is cannibalism and human sacrifice.
Earth: Its elemental associations are stone and metal. Its energy position is heat/dark. Its thematic resonance is preservation. Its corporeal focus is bone. Its living avatars are titans; its revenants are liches. The stereotypical Earth user is stubborn and inflexible; the outcome people tend to fear from them is conquest and oppression.
Star: Its elemental associations are void and air. Its energy position is cold/dark. Its thematic resonance is destruction. Its corporeal focus is breath. Its living avatars are sylphs; its revenants are wraiths. The stereotypical Star user is solitary and inscrutable; the outcome people tend to fear from them is espionage and assassination.
Each type of magic has different strengths and weaknesses and affinities. Someone who's drawn to quick easy messy intuitive solutions might love Sun and hate Earth; someone who's drawn to predictable step-by-step formulas might love Earth and hate Moon; someone who's drawn to secrets and mysteries and hidden things might love Star and hate Sun.
Often, being the sort of person who finds it especially easy to work with a particular type of magic also makes you the sort of person who's especially susceptible to its pitfalls. Using a lot of Sun carelessly tends to amplify your emotions and erode your control of them, but Sun is also very easy to use carelessly without obvious short-term consequences, especially if you have strong emotions to begin with. Using a lot of Moon carelessly tends to erode your sense of identity and cause unpredictable personality shifts, but Moon is often easiest to use if you already don't have a very static mentality. Using a lot of Earth carelessly tends to erode your ability to cope with change, but Earth is the most straightforward and predictable type of magic, so someone whose ability to cope with change was already not great would probably have started there. Using a lot of Star carelessly tends to erode your communication skills, and Star is the most introvert-friendly type of magic, easy to lose yourself in for weeks at a time.
It's possible to be a careful enough magic user that you never hit any of the major traps in your chosen magic type, but it generally takes careful planning and study and self-control; and it's possible to do magic ethically, but the more ethical techniques are often significantly more advanced than the quick-and-dirty ones. And often the only sources of magical education around are people who have already gone quite a ways down the road to disaster and will get impatient with you if you want to be sensible and cautious and stay away from the mind control and human sacrifice.
Probably the biggest source of unpicked low-hanging fruit in the "sane, sensible, ethical magic" area is the concept of combining different magic types. It's not unheard-of, but it's very understudied, because learning to use even one type of magic pretty well can be very difficult, and there just aren't that many people who are willing and able to learn two and then start experimenting with combining them. If you manage it, though, you'll find that you're able to accomplish many more things much more easily with fewer side effects and less compulsory unpleasantness than if you were working in a single discipline.
The other foundational concept of this world is that for some reason the Ezar template really wanted an alt who was an ancient sorcerous undead skeleton. So he's a lich, and his main specialties are Earth and Star but he dabbles in the other two, and he has an even worse international PR problem than the lich Ezar from Materia but doesn't need to care as much because he's significantly more powerful.
This brings me to the concept of revenants, and the related concept of - I said "living avatar" in the rundown but I don't like that phrase and can't think of a better one.
Each type of magic has an associated type of living person, which you can become if you devote yourself intensely to that discipline, and an associated type of undead, which you can become if you die and are reanimated using that discipline. It's possible to combine more than one of these categories in a single person; this happens most often when someone reanimates a dead angel/shifter/etc.
It is easiest to reanimate someone to their corresponding type of revenant, e.g. angel to demon or titan to lich, and if you do so they will retain some properties of their previous form; it's also possible to reanimate someone to an unrelated type, and if you do that they'll retain some properties of their previous form and pick up some properties of its corresponding type. For example, a sylph reanimated as a vampire might find that they have a limited version of a wraith's teleportation ability.
Angels have feathery wings and powers relating to light and life. Demons have batlike wings and powers relating to fire and minds/souls.
Shifters have a human form, an animal form, and a wide range of options in between. Vampires have a human form, a human form with fangs, and an animal form if they really work for it; they don't get to have fun with intermediary stages unless they used to be shifters. Contrary to the teaching of rumours and campfire stories, shifters don't have to eat people to survive and most of them don't do it at all; but vampires do in fact need to regularly drink blood.
Titans are big and heavy and strong and made of stone. Liches are skeletons. Even if they were never anything other than human, liches are surprisingly durable for creatures made entirely of bone, but ones who used to be titans are nearly indestructible. Neither liches nor titans need to eat, drink, or breathe; but titans need to sleep, and liches don't.
Sylphs are small and light and fragile and can turn insubstantial at will. Wraiths are ghostlike, insubstantial by default and capable of affecting the world only with great effort, but they can teleport and turn nearly-but-not-quite-invisible and nearly-but-not-quite-inaudible. Both sylphs and wraiths can fly/levitate. Sylphs need to eat, drink, and sleep, although rarely, and become uncomfortable if they intersect solid objects; wraiths have none of these constraints and can go where they wish.
Of course, in addition to 'avatars' being reanimated as revenants, it's also possible for revenants to ascend to become 'avatars'. If that happens, the results are similar to the other way around: you're primarily the new thing, but with some aspects of what you were before, and (if applicable) some aspects of your previous form's corresponding type.
It is also possible for an avatar to ascend to become a different type of avatar. Results may be unexpected and possibly hazardous. Don't try this at home.
...man, I really want a better word for the living magic people-types than "avatars".
I have a preliminary map of the world; it looks like this.