Magic can do practically anything depending on the system being used, so let us use the most overused version, an elemental one. The elements in question will be the Avatar ones + metal and electricity. Let us assume that it takes the same amount of time and 3x the money that it takes to get an engineering degree, with the cost of military training, to become a mage. To become a military mage you need to be able to cast middle level spells with a focus, or some other tool that lowers casting time.
Mages must first be able to use a magical telekinesis to control their element, like the bending system, before they learn spells. I will call this elemental-kenisis. All people can use some sort of elemental-kinesis though it typically can not do more than light a couple of flames, fill a cup of water, blow dust, create a small pit, etc. people who can do more than this are called either mages or benders. Benders as in the ones from Avatar, everything they can do there they can do here 1 in 5 people are benders. Mages are different because they have mana, let’s say 1 in 3 benders is capable of becoming a mage. All people can only use one element.
Spells are cast somatically, but with practice, or when you learn higher level spells, can be cast with a thought, assuming you aren’t using a focus. The somatic part of the spell is used to create the image in your mind of what the spell should do, and the same spell may use different words for different people. Unlike elemental-kinesis, spells use mana to cast. The more you use a spell, the less mana it takes to cast. While elemental-kenisis is basically like another arm. To learn a spell you must have done the spell with your elemental-kenisis before, or in the case of high level spells know how to, in theory, do the spell with elemental-kinesis.
Spells allow the caster to make complex actions with little effort. Yet, everything you can do with a basic spell you can do with elemental-kinesis if you tried, like creating 10 or so fire arrows to attack with. A middle level spell, while still technically possible to do with elemental-kinesis, brings it up a notch, I.E. a fire mage extracting the heat from an explosion. A high tear spell is a dome of fire hot enough to act like a shield against bullets and cool enough on the inside for a group of people to live in.
To learn basic & middle level spells you need to do that spell three times with your elemental-kinesis. To learn a high level spell you must know individual basic and middle level spells that can do parts of the high level spell, before theorizing how to create your high level spell. Once you figured out how to create the spell using the lower level spells you will then cast them and use your elemental-kinesis to mold them into a high level spell.
Lastly, the higher level spells you can cast determines your rank, a low level mage can cast basic spells, a mid level mage can cast middle level spells, and so on for high level mages. A mid level mage can cast basic magic with a thought, or at least as long as it takes to form an image of what they wish to do + the time it takes to preform the spell with their elemental-kinesis. The higher your mage level the faster your reaction time is. A low level mage is at the peak of human ability irl, a mid level mage is 3x that, and a high level mage is 3x that.
There are also items that can help a mage, like mana potions and focuses, but since I don’t want to spend more time adding to this system that I created just for this, for some reason, those are all the items.
Oh, in this system it would cost ~$200,000 usd to train a middle level mage, and it costs the U.S. military ~6.3 million dollars to build a tank. Granted this magic system would probably bring down that cost a bit, but who really cares at this point. And with magic being this useful, those who can use it get an extra bending class every year in their k-12 education that should easily give them enough proficiency to use basic spells. Hell, looking back on this I think that $200,000 is a bit high, but I will stick with it.
