In the story I’m working on, there is a strict ruleset on how magic works, one of the main points being it needs a “fuel” to work, and that “fuel” is VERY expensive. That being, most magicians use their skills while saving the most fuel possible. Against ordinary foes, without any magical abilities, they usually use it to create a burst of wind that destabilizes the opponent and simply finish them off with a dagger to the heart, much like Andrzej Sapwoski’s witchers use their “Aard” Sign (more of a distraction than a weapon). But, against other magicians, things are a little different. There are big coliseum styled magical fights, those being more entertainment oriented, so they’re usually big flashy combats with fireballs and lightning flying everywhere. But that’s when I got cornered. In actual magical military combat, saving magic fuel would be a primary concern as well, and magicians would probably favor extremely lethal and economic spells over big fiery blasts. Please consider the following:
”Magic” is the ability to control forces of nature (wind, water, flames, lightning) and inanimate objects.
One ****insert fuel unit here**** is enough to cast 100 wind blasts powerful enough to stun or knock out an adult male, or 10 fireballs the size of an orange;
Magic cannot create, only manipulate what already exists. You cannot shoot fire from your hands, you have to actually set something ablaze and control the flames;
Magic does not affect living beings (people, animals, plants), in the sense of altering their living bodies. There is no polymorph, mind control or magical enhancements to strength or speed. You can’t just vaporize your enemies. That extends to the natural elements inside the human body (water, electricity, iron...) There are, however, ways to affect armor and clothing.
The range is how far the magician can see. Sight augmentation apparel can extend the range.
They can control whatever they can see. There are no microscopes yet, so they cannot control individual atoms or molecules.
A single magician power is limited by his knowledge, amount of fuel, and psychological endurance. Casting large spells have a heavy toll in one's mind, and trying to cast a spell too big to a single person would effectively kill the mage. With that in mind, big spells are usually cast by groups of mages holding hands, so they can share the stress and fuel expenditure of such grandiose acts.
There are no permanent spells or "curses". A spell exists as long as someone is casting it. If the caster is incapacitated or killed while casting, the control over that specific element is lost and it will simply follow physics from that moment on.
Based on those rules, what probably would magicians cast in a mage fight? What force of nature is easiest to control and deadliest? Would they just walk around with a pocket full of knives and hurl them with lethal precision at their magician foes? Would they ignore magic and sword fight each other until there is an opening for a wind blast? Please note that I’m not asking about the magic system, which force of nature ACTUALLY is the strongest or that kind of thing, I’m asking about military combat tactics that for some reason include magic.
UPDATE: I was blown away by the amount and quality of the answers here. Almost every single one has inspired me in some way, but as we now have a two days old question I must choose one to be the solution.
Since warfare tactics are pretty much covered, I'll choose the solution based on the duel aspect of the answer (or not necessarily duel, small fights between mages may fit as well). I won't choose one of the existing ones about duels mostly because they miss some points:
- Mages are human. Could you think about bullet-proofing your clothes, blow away projectiles with wind and turn the ground below your opponent into mud at the same time? They can't, either.
- You probably wouldn't want to save fuel while fighting for your life, only enough to not be unarmed.
- No, you can't mess with your opponent internals. No pressure, air pockets in the brain or that kind of thing. The physical space that the body of a person occupies is completely immune to any kind of direct manipulation by magic.
- Obviously, a fight between an expert mage against a non-mage or a novice mage will be a slaughter. Think even power levels.
- The world is big and there are many countries that practice magic. There are many styles of magic and many functions to a mage. Maybe illusionists have a common prejudice against elementalists because "they make too much of a mess".