So I figured I would share the way magic works in one of my worlds, and get some feedback on it.

I guess the easiest way to describe it is it is like a symbiotic/parasitic bacterium. Anyone can, theoretically, get magic, but some have a greater affinity then others. Some locations in the world can support free roaming magic, where it can be picked up by people.

Once a person has magic, there are two main aspects: strength and amount. Suppose magic is represented by a swarm of bugs. Your strength is how strong each individual bug is, while the amount represents how many bugs you have. The physical act of using magic kills these bugs, starting with the weakest.

If you have a lot of bugs, you can use a lot of magic. But you need to keep enough bugs in store to reproduce. It is possible to use up all of your magic. Note, that since the weakest bugs are used first, a wizards final spell will be his most powerful (It is possible to get new magic from a natural source in the world).

In order to make your bugs as strong as possible, you must constantly bleed off the weak, using magic very often, if in small amounts. To grow the amount of bugs requires large intakes if energy with a full capacity, meaning You can't train both for amount and strength at the same time.

This is represented by the two main types of magic users, "monks" and "mages" (actually slightly more complicated). Mages constantly practice with magic, and are capable of short yet powerful spells: Bolts of fire, vaporizing touches, teleportation, etc. Monks, on the other hand, use abilities that must be sustained longer at a lower power: dancing swords, impenetrable skin, levitation, etc.

Magic, as stated before, is not intrinsically bound to the user: a magic user needs to have acquired his basic stock from somewhere. It is quite difficult for magic to transfer from one user to another, but quite easy to pick up the "unatuned" magic in the world. Certain locations, with strong concentrations, can give magic to someone with no affinity.

And finally, to make matters even more complicated, different types of magic exist. Types of magic do not mix well, only the most trained, or the most gifted, can manage even a small amount of two kinds. Generally, trying to cast a mixed spell will backfire horribly, even if the magics are supplied by different mages. There are a few exceptions, but they are few and far between.

TL;DR: Magic is like a parasitic bug that kills off the weak to become strong, attaches to people from the world, and has a death feud with other bug species. Yeah.

Any suggestions? How does your magic system compare?