Conjuration can break literally every single combat skill
And here's how:
The conjuration school is, by itself, a good school. You summon stuff, be it a weapon or a Atronach, and you kill things. This school becomes broken once you start taking that weapon you've summoned (though it technically isn't necessary) and started to use it against whatever Atronach.
Let's use an example of my character that I haven't even put 4 hours into. It's already level 15, with 50+ in one handed, conjuration, and archery. This is accomplished by summoning an Atronach, hitting it enough to kill (in the beginning, and even now because of a lack of any perks in one handed, it takes 5 hits with no power attack.) This levels up conjuration (summoning and hitting with a summoned weapon) and one handed (obviously the attacking with the weapon). Literally the only limit on how fast this goes is by how much magicka you have, and how fast it regenerates. Fun little note here too: it's not limited to one handed for combat skills. Want that two handed to power level? Switch after summoning an Antronach. Want to improve your sneak? Attack when it's not aware of you. Want to start flinging some more powerful flames and frost around? Summon and set that bad boy on fire.
But what you're probably thinking is that this is only attack stuff, and I said all combat skills. Now hold your horses, and let me explain:
After 4 hits, an Atronach attacks you back. Problem? Not if you want your armor to get better. You get the crap kicked out of you, and then get that last shot to make it so that you don't die. Oh wait, now your health is low. Good thing that you can use restoration, and improve that school too.
So, by using this one school, we can improve anything combat related.
Don't believe me? Let's go over the skills you can improve using it, and a short bit how:
-Conjuration, by using the skill (summoning, and using weapon)
-One Handed, attacking summoned creature
-Two Handed, attacking summoned creature
-Archery, attacking summoned creature
-Sneak, shooting/stabbing summoned creature in the back
-Illusion, you can use on the summoned creature
-Destruction, using the spells on the summoned creature
-Restoration, healing yourself after allowing yourself to be hurt
-Heavy/Light Armor, allow yourself to be attacked
So yeah, just a tip, Conjuration breaks everything.
