I don't want to compare games but I think it would be great if I could cast Ebony Flesh or whatever as a sustainable. I don't really have a good reason other than 1) I'm lazy, 2) it takes away from the immersion, 3) other games like Dragon Age had them and 4) I've died on the few occasions that I didn't watch it and the spell expired.

What do you guys think? Would this be a good mod?

I do if magicka regen could work through it. If having a sustainable meant losing magicka regen (as it likely would now), it'd be not worth it.

I'm not sure if it should be totally permanent, since there would need to be some cost involved, which may make the permanence not worth it. If it drained magicka over time, the armor spells may very well become unusable for pure mages; it's already hard enough to get most/all your damage from destruction spells before running dry (unless of course you're willing to abuse enchanting). Personally, I think it might be best to just increase the duration and reduce the magicka cost (since even with perks your top-level armor spell can be really draining if you're needing to cast it in combat).

Unless I missed it, there isn't any way of knowing if your armour spell is still active other than going into spell effects. It would be nice if there was something to tell you if its still working or not.

What I would propose is that it would lower your total magicka to sustain a flesh spell

I'm going to try modding this when the CK comes out - I really want it for the candlelight spell (I'm using a darker dungeons mod), but it makes a lot of sense for the mage armors and probably some others, maybe invisibility or detect life. What I'm planning to do is just have an overall reduction in your magicka pool that's about equal to the current magicka cost of the spell divided by its default duration (though that might end up being a little low). I guess I could get fancy too and do what Dragon Age did, have it effect casting costs for other spells, but I'm not really sure if that'll be possible. You'll just cast it once like normal, then cast it again to turn it off.

You glow green when your armor spell is active. It does a "blip" effect and vanishes when its run out.

I like this, a lot. Lowers your total magicka and stays on until you cast it again. If your total mana drops below 0, your armor effect wear off to keep your mana positive. If you swap gear, your armor effect wears off.

The amount your magicka lowers is the mana cost of the spell. Stability reduces the mana cost of all alteration spells by 25% that stacks with your school reductions. Dual casting gives 2.2x armor for x2.6 the reduction in your max magicka (so with mage armor perks you could hit the armor cap).

Keep dragonhide as it is or rework dragonhide to something else (spell reflect?). Oh my god... I would love if somehow someone could make a mod to work this way. That would be AMAZING.

Wouldn't it be easier and accomplish roughly the same thing to just add a small timer in the top right corner of the screen?

I haven't used any mage armor spells yet, but for candlelight its pretty apparent when the spell wears off. It's still annoying as hell to then have to reequip and recast the spell.

I can see why you'd like it, but there'd have to be some penalty like in DA. I took Dual Casting in Alteration mainly because I'll tend to forget to cast it sometimes. When I dual cast Ebonyflesh though, I get 3 minutes! And Dragonhide 99 seconds! I like the idea, but i'm fine with dual casting

I'd really like for armor spells to be sustainable. Personally, I'd prefer that maintenance result in penalty to magicka regeneration that's calculated based on the base spell's cost divided by its duration, basically averaging out the cost of recasting the spell.

Wouldn't it be more annoying to only have that light while continuously draining mana? You can make Candle/Magelight last for up to 2 minutes if you overcast it. Personally though, for light, I prefer Night Eye.