Since there has been interest, I’ll share a little more. To answer the second part first, it was entirely improvisation on mine and the players’ part. They would ask if something was possible and I’d decide if it was reasonable; in retrospect this put a lot of pressure on my players to improvise, and a lot of pressure on me to describe scenes fully and completely, but I just about made it work.
Here’s a bit more of my written information about how the magic system worked:
Elements:
The Winds of Magic flow through every part of the world; each object and each living thing emits a stream of magic that consists of aspects that describe and define it. These aspects can be almost anything, save for incredibly broad and deep concepts; notably, light, dark, death and life are present, but cannot normally be accessed by mortals. For example, a sword emits an aura that says “sword” but a magical practitioner might be able to split that into “sharp,” “tool” and “metal” for use in a spell, artifact or potion. A flower might have the aspects of “growth,” “colour” and “beauty,” but not life. A lit torch might hold the element of “flame,” but not light. Each character also has a personal element, something which symbolises them on a fundamental level; either through personality, belief, or actions. A character always has access to their own element for all purposes, although they may become drained from using it too heavily.
The powers system relied on players picking two powers for their character from the list (or the same power twice to “master” it). The original list was much longer, but I’ve cut all the powers and abilities which were unrelated to the magic system. I left the Mastered versions in as an example of what a character devoted entirely to one aspect could be like, though obviously the two powers limit is pointless to carry over to OL.
Powers:
Arcana
The character can form spells by combining the essences from their surroundings. They must use objects, and the elements of themselves other party members, to describe an effect thoroughly. For example, taking an arrow and a lit torch, an Arcanist could use the aspects of “missile” and “flame” to make a fireball.
Mastered: You become a ‘mancer, able to wield your character’s Element in nearly any way you can imagine without having to combine it with other elements (though you still can), e.g.: pyromancer (fire), hydromancer (water), bibliomancer (books), arbormancer (trees).
Alchemy
Unlock the essences of ingredients to create magical potions, poisons, or even bombs. The character may spend time during a rest to make potions out of the essences of materials they have to hand. These materials are destroyed in the process. The player must define whether the potion is intended to drink, as a coating on a weapon, or as a thrown weapon at the time of making it, the effect is determined based on the aspects used. Only one potion may be affecting a character at any one time. An example might be using quicksilver and the tail of a running lizard to make a potion of haste, or melting down a bell to make a sonic bomb, or mixing spicy peppers with lamp oil to create a sword coating that makes wounds burst into flame.
Mastered: The ingredients in your potions no longer need to be components of physical objects, you can condense auras from the surroundings into liquid form. The aspect used is lost from the item used, similar to artificing, and the item itself is often destroyed.
Artificing
Bind the essence from an object into any piece of equipment, to add properties, or be unleashed when chosen. Artificers essentially “move” essences from one object to another, e.g. taking the heat from a fire to make a heated blade, putting out the fire in the process. Or strengthening armour with the toughness of stone, but crumbling a rock to dust. They cannot drain aspects from living beings.
Mastered: You gain the ability to create complex magical and mechanical constructs, such as simple mechanoids or blackpowder firearms.