So I was thinking, in order to completely maximize the damage capabilities of a destruction mage, you want to keep your level as low as possible. Normally if I do a mage I'll spec in Conj/Ench/Destro, and that brings me into the ~33 range. But if I wanted to do JUST a destro mage, would it be possible without enchanting?

I'd probably only use fireballs, all levels would go into magicka. I'd cap at level 17-20ish, so everything I fight would be pretty low leveled. Are there any naturally occurring items besides random spawns that reduce destruction magicka cost?

But yeah, post opinions and if you could answer some of my questions that'd be great too.

Thalmor robes often have the type of cost reduction you're looking for. I don't know if they all do but some definately do.

As for doing it without enchanting it depends on the difficulty level. It seems that any setting up to Adept will work. I don't know about Expert. But I do know that on master you have to have massive amounts of fortify Destruction gear to make it viable. Either that or carry ridiculous amounts of Reinforce and Restore Magicka potions. It's better to go with Enchanting. Some will say you can do it on Master without Enchanting or Alchemy. I don't find those opinions very credible.

Fireball is one of the worst spells in the destruction tree in my opinion. It's good for softening up tightly grouped, low-level mobs and that's about it (or if you have lousy aim and extra magicka to burn).
Firebolt with impact perk is superior. Alternate dual casts to stagger with single casts for damage to conserve magicka. Small groups can be kept out of melee range this way.
When using Flames, even beyond level 10 it's effective if you fire short bursts instead of continuously as the burning damage stacks.

@Ego, Fireball is more efficient than any other spell when used on 2 or more enemies, as you deal twice the damage you would have if you had used a single target spell, but you do even more since fireball does more damage than firebolt. I am aware of the OP'dness of firebolt with impact at lower levels, and I'll use that as well, but fireball is going to be the main damage-doer.

@Bacillus, I'd probably go for the master robes of destruction since I'll need to use a hood to maximize magicka, or just run the archmage robes with the circlet you get from the College's questline.

There was a post on reddit about a guy who said he finished the game at level 20. As you can imagine, he got lots of hate and deleted the post quickly. I was quite interested in knowing how he did it though. Before he disappeared, I was able to ask him what he did and I think he said he did dualcast firebolt mostly and and chugged potions when he needed it. He disappeared before I could ask more.

I want to try something like this, too. A minimalist build. Pure destruction. I'm not sure how strict I'm going to make this.

I'm thinking no crafting whatsoever. Cooking food is allowed. No wearing armor. Can wear clothes and jewelry that I find and buy at the store. Allowed to buy and steal potions.

I'm thinking of allowing myself restoration spells, maybe just the healing spell. but not allowed to take perks in anything other than destruction school. Alteration and other schools are not allowed. No training allowed. No staffs allowed. No archery allowed. College of Winterhold and main quest.

Do you think this is feasible in adept?

What difficulty level are you playing on?

Like I said before, I think if you're Adept or lower, your plan will work just fine. But if you're going to play on Master, even the Archmage robes are incredibly weak when fortifying your Destruction.

Before I deleted her a few days ago I had a Destruction character that had 100% cost reduction and around 300 magicka. During one battle I forgot to put her helmet back on her, thereby losing 25% cost reduction. I got off about three or four dual-cast Fireball spells and the well ran dry. That was with 75% cost reduction and a Destruction skill of around 70. Without 100% or at least 90%+ cost reduction a character using Destruction as their primary offense isn't going to do much damage on Master level difficulty.

Edited to add: What did that guy mean by "finished the game"? You can't "finish" Skyrim. You can do every quest available but the game never ends. If he said it was just the MQ then I'll buy that without bothering to give it much thought, but anything more than any one quest line? Nope.