Considering mods tend shut off without warning on this site, i won't take the chance.

Thank's for your answer!

With this mod, any of the items already in the game with a generic Fortify Destruction enchantment (e.g. Circlet of Peerless Destruction) can be disenchanted to learn the damage-boosting Fortify Destruction enchantment.

To answer your question more directly: yes, it's possible to create a mod with a Fortify Destruction Damage-enchanted item, but it's unnecessary to do so when using this mod.

Is it generally possible by modding to crate a an object enchanted with fortify destruction damage. So it can be destroyed by an enchanting table to learnd it. I search since month for such a mod.

Did a little research on uesp.net , and was relieved to find that it's the base magicka cost of a spell that contributes to your skill progress, not the adjusted magicka cost. That gives me an idea for dealing with Fortify Illusion: change the basic five Illusion perks to increase effectiveness rather than halving cost, then leave the cost reduction enchantment as it is. Possibly I would also reduce the base magnitude of the spells to make the perks more valuable. Thus, you wouldn't need the perks to get 100% cost reduction and cast the spells forever; you would need the perks for them to be effective against any decently-leveled enemy.

Don't take that as written in stone; that's just my current thought.

You are the boss. I'm just throwing into any ideas I see even remotely useful and reporing anything worth mentioning. I am benefiting of it too, as a mod user, so whatever helps, that is good, while useless matter can and shall be ignored.

You make good points, but I'll have to think about it a little. I haven't developed anything for Skyrim in a few months, but I'll probably look at making an expanded and/or improved version of this mod the next time I get into Skyrim modding. Regardless, I appreciate your suggestions and feedback; you've given me some good ideas for that next mod.

However, those Fortify Destruction & Magicka Regen robes you can find as a loot are distinct, since they have significantly larger bonus value than you can customly apply by your own self, even with the skill fully trained and all perks gained. I personally don't use them, since they look horrible (fashion victim I am), and as such can't say whether the balance is ruined. Still, Archemage's Robes could have used 15% bonus to anything else, but cost decreasement (with other schools' bonuses modified). It's not learning to be magically economic made you the Archemage, but that you know how to tap the most out of any spell and apply in the most efficient way possible.

And I am currently out of any sane ideas for Fortify Illusion spells bonus replacement. Still thinking.

Actually, I intentionally left the predefined gear and Fortify Destruction & Magicka Regen enchantments alone. As you noted, they can't get you to 0 cost spells, and I think having it this way makes the Winterhold College robes a little more notable and comparatively useful.

Apart from perhaps making pre-existed gear to change cost decrese to strength bonus so it won't go waste, something must also be done to Fortify Destruction & Magicka Regen enchantment, which still have cost reducement. Not that much impressive one to be abused for 0 cost spells, but still.

Investigated it further. Haven't played for a while and possibly it's just my imagination, that I ever had Fortify Destruction enchantments in the first place. Helm and gloves have just 1 echantment each, unless I "dirtied" every single save I've been using for the test by overwritting it with the mod enabled at some point. Doubtful.
Found both predefined gear (DB robes) and customly enchanted heavy armor piece with Fortify Destruction and those, with mod enabled, still possess cost decreasement, while I am clearly able to make new pieces with strength increasing factor at the same time.
Sadly, I didn't manage to find anything double enchanted with Fortify Destruction to check further and already have the skill legendarised, but pretty sure it won't cause any bugs.

@Hollow Ichigo: I wasn't aware of that bug. Does it occur just once, when you load the mod, or has it occurred repeatedly?

I wasn't aware that cheaper spells grant less training. That certainly makes a persuasive case for applying this change to the other schools. Here are my current thoughts on how that might work:
- Fortify Alteration would increase effect duration.
- Fortify Conjuration would increase effect duration. I think in order for this to really be a significant benefit, I might want to reduce the base cost and duration of the spells.
- I'm not sure how I'd deal with Fortify Illusion. Neither increasing magnitude nor increasing duration would have a significant benefit for a fully-perked illusionist; the current magnitudes and durations are good enough to walk all over almost everything in the vanilla game. Ideas would be welcome.
- Fortify Restoration would increase effect magnitude.

Alright, now's the bug/issue. I had set of armours and jewelry with double enchants on each. Helm and gloves each had Fortify Destruction as well. However, both unequipping and putting on a ground beforehand and having them equipped led to said enchantments disappearence. Gloves and helm now have only one enchantment on them left.
Not much of an issue for my current progress, as I was going to make new instances of mentioned gear pieces, but worth mentioning, I think. And doubt I have anything modifying how enchanting goes or acts.

And that would make Archemage Robe actually useful beyond being fancy cloth piece, too.

Mod of my wet dreams. Did you know, that as any spell gets cheaper, it trains the corresponding skill tree less? And the very thought of having destruction magic cost 0 for any spell is sick. Plus less needs to rely on oh so short lasting potions as the only way to squeeze any additional power for offensive spells, which gets ridiculously weak as you progress through the game and level up.
Thanks. How about same idea being applied to other magic schools as well, having relative potion effects as a destination point? That would lead to no 0 cost magic, no mindless spam, investing time into better aim and careful thinking whether you need this or that casted and onto who, since you can't just easily apply the magic to everything around and then have half of your magika bar still intact.