Magic in General
Magic. The most powerful force in all of Mundus. There would be no Nirn if not for magic, and lets be honest, magic makes TES pretty damn interesting. It has many uses in Tamriel, one of them being combat. But what is it about the clever craft that makes it so effective on the battlefield? You might say that obliterating your enemies with Destruction magic is what magic is meant for in warfare, but in reality (well, not OUR reality, but you know what I mean) every school of magic has a place in battle. Lets dive in, shall we?
Destruction magic is probably the most common type of magic used on the battlefield. In fact, Destruction magic is the TES equivalent of artillery. Setting enemies aflame, electrocuting them, or freezing them is all well and good, but I feel there are some draw backs to using Destruction magic.
1. It is very dangerous for your allies as it is for as your enemies. When two armies are about fighting, launching a fireball into the thick of your enemy is more likely than not going to kill some of your own as well.
2. Destruction magic puts it's user in harms way as well. Casting a spell takes concentration no doubt, and in the thick of a battle it is rather hard to concentrate. The spell could go awry ( pure conjecture on my part, but it makes sense that a spell could, in a sense, misfire), or while you are trying to concentrate, you are killed as you cannot defend yourself adequately.
So, where would a destruction mage belong on the battlefield? Most likely behind a line of infantry. As I said before, a mage is vulnerable when casting a spell, so he should be protected. I also believe that a mage would use destruction magic on the enemy before the two armies clash in battle, and when the enemy army is close, the mages would fall back behind the infantry.
In my opinion, Restoration would be far more useful than destruction magic in battle. Healing your allies would be extremely useful, and restoring your allies stamina would let them fight harder. Most battle mages and paladins would fit this role quite well, acting like battlefield medics while still being able to protect themselves. Restoration magic would also be useful after a battle is over, as the most seriously injured soldiers could be saved.
Conjuration would be useful to bolster your ranks. If you have, say, 100 mages, and each summon an atronarch, you basically have a hundred new soldiers fresh for battle. Conjuration would also be necessary to banish your enemies atronarchs. Daedra would a terror on the battlefield, if the mage is skilled enough to summon one and bind it.
Alteration is quite useful in battle as well. You could layer yourself in magic armor without it weighing you down, and you could do the same with your allies. Another possibility would be to create an aquatic army. Temporarily anyway. Imagine casting a breath water spell on an army, and then send them to cross as river that blocked their path before. The possibilities are endless.
Illusion magic has the most potential to be a game changer on the battlefield. A large group of mages could theoretically cast a massive frenzy spell onto the enemy army, and watch them cut each other to pieces, ending the battle before it even began. When an army is about to rout, casting a calming spell would force them to say and fight, even if they are slaughtered in the process. a fear spell cast on charging enemy cavalry would cause the horse to panic, and leave the riders with no control of their mounts. Unethical? hell yes, but it works.
Something to remember
Even though everything I listed above most likely does happen in the wars of Tamriel, there is something to keep in mind. The average mage is not like your character. He cannot cast twenty high powered spells, and instantly refill his magic pool by chuagging potions. Most mages can maybe cast a few spells, but then have to retreat, as casting spells without a doubt drains you. Trying to cast a spell when you have no energy left would probably end up killing you. That being said, some mages probably can cast spells that are not even in the game just for gameplay reasons.
Please leave feedback in the comments, as this was my first blog that I actually spent time on. if you want me to continue to make blogs related to subjects such as these, let me know.