How does magic work in this universe?
Good question! Gives me a good chance to get some details together all in one place about this.
My main goal was having different kinds of magic for different species, so there are a few different systems. The main idea is that the world where Pick-n-Mix Comix specifically is set, the 2112th Rhapsody, is comprised of a physical top-side half, the Protocosm, which contains the interstellar Chasm of Stars, and a spiritual bottom-side half, Ectotheria, which contains the Other Realms.
Ectotheria was once inhabited mostly by ectoplasmic "divine spirits" which evolved into what are known in the 1980s as angels and demons, while the Protocosm originally had no such creatures; however, both worlds are overlaid by flows of cosmic ley-line energy known to the elves as ley lines and to dragons as the Wayveins. Wayvein energy is what elves draw on as a natural source of energy for their magic, because they don't have the same spirits which humans in Ectotheria evolved with so it's harder for them to affect things the way humans and those with those spirits do; additionally, Wayvein energy is like acid to dragons, whom elves harvest scale oil from which boosts their ability to do reality-altering stuff the way dragons do, so Wayveins are useful as a weapon against dragons by the elves. Then they use Wayvein energy as a fuel source to get scale oil doing what they want, if they want it to.
Ectotherian spirits are renowned for being envious of the Protocosmic reality and constantly try to pull bits of physical space through the boundary of the Coin, the Ward, into Ectotheria, which resulted in the development of the original Magelands region, inhabited by species descended from those created in the Protocosm. Humans were among them, and because of that and their association with the inherently spiritual-based magic of Ectotheria, humans in Ectotheria evolved with something called the mentian gland, which essentially metaphysically locks ectoplasmic energy into their bodies and creates a spirit for them — a soul, distinct from the divine spirits — which can affect the world using natural spiritual telekinesis and hypersensitivity to spirit-based magical affairs.
So, most Ectotherian humans have powers similar to ghosts, psychics, and telekinetics, and that sort of thing. Different practices of magic include witchcraft, galdorcraft (practiced by the Frithanic people in Fritherland), sorcery, alchemy, fortune-telling, soothsaying, and so on, and (as of the 1980s) you generally need to be a licensed practitioner, which is a really important part of most stories, but all practices more or less draw on either spiritual or ley-line energy or use magical artifacts like scale oil, lucidite crystals, soul gems, or things like the Quill of Lore or the Constantin Cube.
Psychics can pick up on latent emotional and psychic energy and pick up on dreamwaves and thoughtwaves and sometimes detect energy from the future or cast spells like Lineage to determine similar wavelengths from the past history of an object or place. Also, sometimes they talk to ghosts and use spirit boards, although that's really more of a fortune-teller and spiritualist thing.
Witches generally use a wide variety of self-care rituals and charm bracelets, which are like mini-spells for random boons which can be cast any time. Also, they use wands, which aren't as common in sorcery or psionic practices.
Wizards are just those who dedicate to the study of as many different types of knowledge and practices as possible. They rarely practice everything, but they have a knowledge of potentially how to if they need to, making them adaptable and innovative all the time.
Sorcerers are those who treat their magic like a science and often use it to specialize in further areas, like the transmutational or dimensional sciences and the specific physical manipulations of spiritual energy. It's a lot more delicate and usually taught in schools alongside other scientific topics given the propensity of its practice in Inglenook, making it a basic knowledge factor. Less common in the Other Realms outside of Inglenook though.
Magicians and illusionists usually use light-based illusions and glamour magic from various different systems for entertainment purposes, trickery, and stage magic that's a little bit genuinely magical anyway, like Azurov the Amazing and his villainous former partner Salvador the Sane.
Warlocks are those who break their Practice Oaths. When you get licensed for whatever brand of magic you'll be practicing, at least in the modern day, you have to take a practice-appropriate Oath of one type or another; I haven't really written any of them, but in theory, there are Oaths for sorcerers, witches, wizards, and psychics at the very least, and maybe one like a generic Magical Oath for anyone just interested in magic. They're all intended as ways of ensuring your dedication to the legal practice of your magic, so the world doesn't enter the Dark Age of occultism and demonology again; if you break your Oath, you're guilty of magical malpractice (being the reason my current novel in that regard is based around warlocks and called the Magical Malpractice series) and branded a warlock, considered a criminal, and can be charged for it if you're arrested, with most warlocks ending up in either Quagmire or Lychgate Prison for it.
"Evil" practitioners who aren't warlocks are usually occultists or demonologists, who consort specifically with the Ectotherian divine spirits, who can obviously change the make-up of the Other Realms completely more or less on single whims, and most of whom are demons rather than angels by the 1980s OE.
Additional magic systems appearing in the universe outside of the spirit/ley-line systems:
Fairies and Fae-touched beings alter reality similar to scale oil, but scale oil mutates and shifts while Fae magic alters things and changes things transformatively. When the dragon Eirimë dies, her rotting scale oil transformed a swamp into a mutant, corrupting version of itself; when Fae magic gets involved, horses become unicorns, horses ridden by humans become centaurs, goat farmers and deer hunters become satyrs, and bears become duocorns. So things change into more of what they are, rather than less. Faemore also encompasses the Protocosm in some ways and has a way of leaking through the Ward in a way most of Ectotheria does not, so some of those creatures exist in the Protocosm in especially strange locations.
Rusidrans, a species of imp from the planet Rusidra in the Chasm of Stars, have a bio-connection to a material on their planet called argosium. I don't know how it works but they can control it as though it's liquid despite it being as solid as concrete and black like obsidian. They use it to create brutalist cities for themselves and get involved with other cultures to sell their architecture, as well as using it for spaceships from time to time.
Most dwarves, imps, goblins, kobolds, gremlins, and merrows are some variation of human sub-species (with humans, elves, ogres, and nymphs being the original two, fairies and pixies being from Faemore, dwarves and imps being the male- and female-based offspring of a human and an elf intermingling, merrows being the offspring of a human and nymph intermingling, and goblins, kobolds, and gremlins being the various results of human and either troll or ogre), so their magic is somewhere in between there since most of them have the same type of soul as humans although theirs are usually not human souls explicitly. Goblins are addicted to a magical lightning called emeraldine, which they often get tattooed into themselves, and I think gremlins prefer technological developments based on ripping off elven scale oil-based tech (which also inspired the tech in the steampunk pirate-ish world of Hesper in the realm known as the Infinite Ocean), while dwarves differ based on where they are. Most Fritherlanders are dwarves and they use galdorcraft (galdorkraft in Frithanic) a form of spirit-based magic similar to modern witchcraft, but since the Frithanics were in the land that became Inglenook before the Ingles were, it functions a little differently and is mostly based on specific words of power and the use of Dragorean runes known as Mezhon for spells.
Most Fae magic can be highly gimmick-based as well. Most fairies specialize in a specific area: the Necromancer is a death fairy, Jack Frost is an ice fairy, Heartstroke is a love fairy, and I don't remember what Ligeia is. However, they have their own elements. Any creatures directly of Faemore tend to be gimmick-based, and Fae-touched individuals can be as well, such as the Black Stag functioning as a way to offset the unicorns and lure people toward the Grim Grove, the Old Shuck being territorial over Grimstead, Mister Snowbell being a flurry-starter, and the Frost Lords keeping the weather in the Frozen World permanently frigid so they can survive there.
Finally, the plasmic forces. All 13 forces were derived from Ectotherian ectoplasm being sent across the Other Realms and the Chasm of Stars to infect reality according to the plasma's source, although not every plasma does its job well. This one is a wholly expansive system on top of the spirit-based magic system (which you could argue is an exploration of a similar "plasmic infection" using spiritual ectoplasm as its base), so I'll have to do an entirely separate post on the full details, but each force is usually a different color and infects the blood so that the user is either connected to a hivemind or can create plasmic constructs like lightning or sentient creatures connected to their own hivemind with it. Plasmic forces empower a huge number of characters in the 2112th Rhapsody, including Fleetfoot, Big Blue, the Man Behind, Graphique, Emerald Flash, Mr Limelight, the Blue Haze, the Stellar Meridians, and the Redblades, so it's a backbone of a lot of the more superhero-based characters typically.
A further finale, the Sunbearer legacy. It lets Solar Girl use pyroplasm, the fire plasm, to access powers based on gravity manipulation and nuclear fusion themed after the sun, but that's a full-on superpower at that point, and it's derived from plasmic forces (which also empower many fire elementalists anyway), so I'm not sure it's fully relevant under the purview of how magic works in this universe. 😆