When most people talk about magic, arcane magic is what they're thinking of. Through the use of intellectual discipline or force of will, wizards and sorcerers are able to produce a wide variety of seemingly supernatural effects. In the world of MK, however, arcane magic is as much a part of nature as the force of gravity, and like gravity its effects can be understood and predicted even though the ultimate cause of it is mysterious.
Over the thousands of years of recorded history the sentient races of MK have developed a variety of ways of perceiving and manipulating arcane magic. Some mages view magic as being composed of "shapes" — proto-spells that drift through the world and are shaped into their final forms through the mind and will of the spellcaster. Others say that magic flows across the world like currents and gethers into eddies and pools, occasionally gathering into great vortices or fountains of power that can sap or enhance mortal magic. Still others talk of elemental forces of magic, or magic of different colors, or "ley lines" that run through the world like an arcane power grid. Some believe that magic is a part of the natural world, while others believe it flows into the world from someplace "outside".
All of these beliefs are, in some sense or another, true — and all of them are limited. At this point in history, neither humans nor Elves nor even ths gods themselves have the technology necessary to peer into the innermost fabric of reality to see what magic really is or how it really works. What matters, from the perspective of an eighth-century mage, is not whether his understanding of magic is more technically correct than his neighbor's, but whether his understanding allows him to wield magic more effectively. There is no "wrong" way to understand or envision arcane magic; if it works for a given wizard, then for her it is true.
Because of this, feel free to have your characters in MK envision their magic however you like. Certain themes do come up again and again in most systems of magic — the connection between magic and life force, for instance, or the notion of "elemental" forces like fire or water — but your character's understanding of magic need not emphasize these aspects if they are not important to the plot of your stories. If there is any rule that we would recommend as universal, it would probably be the following:
Magic has a cost. Whether it is hours of focus and discipline, the expense of unusual spell components, a blood sacrifice, or a growing weariness that saps the mage's body, there should always be a limitation on how much magic a caster can use in a given period of time. Wielding incomprehensible cosmic forces is not something you can do without it coming back to affect you in one way or another, and mages who develop "insulation" against the forces that they command (in the form of spell components, magic circles, or what have you) will be limited in time, flexibility, or fiscal resources, while those who channel magic "naked" risk their own lives, health, and/or sanity.