Alteration

Alteration is almost completely a defensive/utility school. It probably has the most utility out of all schools, but also has some powerful defensive options. It's offense is limited, but it still has some: Elemental shield can be used to hurt others, while levitation and burden are fun crowd control tools.

Burden is now a real spell that can root you in place, forcing you to drop your armor or counter it with Feather or Dispel. Magnitudes can now reach much higher, up to 500 with top-tier spells. However, compared to BTB, I've toned down the durations, because they were way too annoying/strong. Most of these spells have a 10 second duration. NPCs will use them.

Feather is much more usable and the duration effect is almost negligible, meaning you can have very high duration spells.

Shields are cheaper, making them somewhat useful. Normal Shield spell can be useful as an actual armor buff! I recommend Spells Reforged - Elemental Shields mod. It makes Elemental Shield not only prettier, but also more impactful. Without this mod, they might be a bit too weak.

Levitation now requires effort. Even weak levitation spell demands a bit of caster's skill. After all, all the flexing Telvanni do better have some merit behind it. However, high magnitude levitation is much easier to cast, and something high skilled mages can look forward to. Also, offensive usage of levitation is recognized and legitimized.

Lock also got this treatment. Since magnitude essentially does not matter, Lock has a minimal cost, so that you can't lock anything for free and need some skill in Alteration. High level spells are expensive for the immersion sake, locking something with a high level lock should take effort.

Open spells scale differently from most, with high magnitudes getting increasingly difficult to reach. Players majoring in Alteration can be expected to be able to unlock locks of up to 40-50 difficulty level from the level 1. To unlock any lock, you would need around 75-80 Alteration.

Slowfall is not indended to use with MCP's Slowfall fix/rework. There are several mods that intend you to use "Slowfall 1", so I've decided to follow suit. And you also can't cast Slowfall with very low duration for free. You will actually need some Alteration skill to avoid fall damage.

Water navigation spells are, in general, quite cheap. Skilled mage can have a strong Swift Swim spell to traverse the waters quickly, at the same time having a long duration Water Breathing on. Water Breathing, however, can be abused with low durations, and so even the cheapest Water Breathing spell requires some effort.

Conjuration

Summon stuff. Summon a lot of stuff. Even more with mods. Command spells are weirdly placed here, but I've decided to keep it this way, just because this school needs some utility. It's the easiest school to balance, just because most of the spells adhere to the same rules, but with different coefficients. And also the hardest in case you use mods that rebalance creatures.

Command spells require some effort and can't be used by just anyone. Creatures and NPCs around level 5 are somewhat controllable by a low level mage, with difficulty steadily increasing, and for level 20 you'll need to have quite a bit of skill.

Bound gear. Armor is usually cheap (but keep in mind that you'd still need your armor skill if you're using the armor penalty part). Weapons are good, so they're more expensive. A new player majoring in Conjuration can reasonably summon a dagger, others will require more skill. With 50 Conjuration you should be able to summon most of them. It's essentially daedric, so I think it's fair. Although I personally don't get the appeal of not having your own shiny weapon and fighting with the same summoned thing.

Summoned creatures. These have the same formula, but with different coefficients. Basically, summoning something for 30 seconds is the benchmark. Summoning for 10 or 60 seconds is comparably ~20% more cheap/expensive. Player majoring in Conjuration can summon something like a Bonewalker from level 1.

Below are how the creatures ranked in terms of difficulty:

Ancestral Ghost < Skeletal Minion < Scamp < Bonewalker < Centurion Sphere < Greater Bonewalker = Clannfear < Bonelord < Flame Atronach < Hunger < Frost Atronach < Dremora < Daedroth = Winged Twilight < Storm Atronach < Golden Saint

I think Vanilla really undervalues Flame Atronach and overvalues Winged Twilight.

Magicka of the Third Era is compatible with summoning packs of Magicka Expanded. New gear and creatures have been looked at. Do note, however, that these were balanced around mort's rebalance mods (Beware the Sixth House, Tribunal Rebalance, Bloodmoon Rebalance). Without these, they'll likely be unbalanced. Also note that some of the summons ME adds are extremely strong. Values are very approximate. Master mage can somewhat summon all of them, because who cares about balance at high level.

Destruction

Destruction is the most straightforward-looking offensive school. But it's not as straightforward as it tries to be in Vanilla! Magicka of the Third Era attempts to make it more varied by differentiation of the damaging effects, while making other tools more attractive. Destruction is not just raw damage, but also debuffs, and wacky gear-destroying effects. It's a large toolkit of offensive spells for every situation, and the goal is to encourage using different tools. Of all schools, Destruction also gets the most synergies.

The cornerstone of balance is the damaging effects. Destruction has 5. Overall, they're less damaging even on high skill, but more magicka efficient. This makes the magicka pool stacking less relevant, and, at the same time, combat gets less reliant on chugging as many magicka potions as you can while firing the strongest possible 1-second skill that empties your entire magicka pool. All of them have some niche, and I've tried to not just limit them to resistances:

-- S - best, A - good, B - okay, C - bad
------------------------------------------------------
-- Type      |  Price  | AOE |  DoT | Resists |
------------------------------------------------------
-- Fire        |    A    |    S    |    A    |    B    |  
------------------------------------------------------
-- Frost      |    B    |    B    |    B    |    A    |
------------------------------------------------------
-- Shock     |    C    |    A    |    C    |    S    |
------------------------------------------------------
-- Poison    |    A    |    A    |    S    |    C    |
------------------------------------------------------
-- Health    |    C    |    C    |    B    |    S    |
------------------------------------------------------
... of course the formatting is going to mess up. God damn it.

Additionally, Frost is cheap for touch spells, but expensive for targeted spells. And of course, they also have different synergies. For example, "Fireball" synergy encourages you to use fire AOE with both instant damage and DoT.

Damage Attribute, Skill, Magicka, Fatigue are overall put in line with other offensive options. The usability of Damage Magicka is still doubtful when it comes to the player, but NPCs will enjoy destroying your magicka pool. Others can make for great debuffs, especially if you pick a right one for the opponent you're facing. Attributes and skills are priced differently depending on how combat-relevant they are, so damaging Strength or Long Blade is more expensive than Luck or Athletics.

Disintegrate Weapon and Armor are much cheaper than in Vanilla game. They were pretty much useless before, and now can be actually threatening. They serve a very interesting niche of weakening physical fighters, and so I hope they'll fill it. Disintegrate Armor in particular is really cheap. And Hunger will enjoy the empowered Disintegrate Weapon (same as in BTB) - don't forget to have a replacement!

Drain spells are tough to balance, serving as temporary debuffs. Strong 1-second-kill spells are fine in my book, but I've also added some incentives to go for longer durations. Just like with Damage effects, they're now can be reasonably used as debuffs, cheaper at the cost of being temporary. Also, these can't be cast on self. I can't find a non-abuse reason you'd want to drain yourself of something. And if you want to, you can always put some effort and use damage effects instead...

Weakness spells have also suffered from short-duration-uber-spells issue. This is remedied, making such spells somewhat pointless. Overall, I did not stray too much from BTB's approach, making them useful without being totally broken.

Illusion

Illusion is mostly a utility school with some powerful defensive options. In addition, Frenzy now can be used as an offensive spell.

Calm, Frenzy, Demoralize and Rally spells are reworked! Now they are level-based, like in later games. They are guaranteed to have an effect on target of level lower or equal to magnitude, and will be resisted if target has a higher level. In addition, Frenzy now makes target hostile to everyone, making it even more powerful. But frenzying strong targets is also very difficult. Currently, casting Frenzy on non-hostile is not considered to be a criminal act. But I might change it.

Blind got much cheaper. It's intended not only to dim your screen, but reduce the hit chance. Many NPCs will have this spell.

Charm gets a minimal duration to prevent powerful 1 second skills.

Chameleon gets progressively harder to cast at higher magnitudes, so that low magnitudes are perfectly reachable, but getting high Chameleon values is impossible.

Invisibility takes some effort to cast even for the lowest duration. Scales very well with duration, allowing for long spells. I recommend using Stealth Improved to fix Invisibility-stealing. And Enhanced Invisibility for the visuals.

Light and Night's Eye, just like the other similar "toolkit" spells, are normalized so that they require at least some skill to be used, but scale very well. Allowing for very powerful spells for a mid-level mage. Enhanced Light is supported and recommended, "Magelight" effect has the same values as normal Light.

Paralyze gets progressively harder to cast the longer it gets. Short duration spells are quite cheap, but getting further is much harder.

Sanctuary is rebalanced to be a useful anti-melee effect without going overboard.

Silence gets scaling similar to paralyze, although not to that degree. Long-term Silence is not a very good concept in my opinion, but spamming shorter silences is very possible thanks to low costs.

Sound was already talked about - this spell now increases spell costs, 5% per magnitude, acting as a soft silence (might be better in some cases vs dumb AI).

Mysticism

Mysticism is a jack-of-all-trades school with great defensive and actually quite powerful, if limited, offensive effects. More so, it also has amazing utility! It's just really good overall.

Absorb effect are balanced around being slightly more expensive than damage/drain effects. You could theoretically make a mage who'll use Mysticism effects as the main mean of offense, but it is going to cost a lot of magicka. Absorb skill is banned for spellmaking, being one of few effects that I don't see a point in allowing to make. Offensive use is much better done via drain or damage effects, and boosting your own skills is not very good for the game's balance, or just can be done by other means, and thus not very interesting. The only few skills where it is somewhat interesting is armor skills, because they scale off your armor, and for those there are unique spells. For the rest, nope. Absorb magicka is also banned, for being a pain to balance, and is limited to unique spells.

Detect effects are very cheap and allow for high duration spells. Works with Enhanced Detection mod.

Dispel is another effect where 100 magnitude is the minimal. From my understanding, magnitude equals chance of dispel, and I'd rather not introduce another random bs. So 100 is the norm, and effects cost from 10 on self (castable by a lvl 1 majoring in the school) to 16 on target. You can even make large area dispels with very lenient area scaling.

Interventions cost 13. And this is a big balance cornerstone, because until this point, you can't navigate the map for free. Level 1 player majoring in school should have about enough skill to cast it since the beginning. But without enough skill, you should rely on scrolls.

Mark & Recall cost 17, making them unaccessible to level 1 characters. It's a very powerful pair of spells, and I want them to be earned, instead of being castable right since the beginning. Unless...

Reflect and Spell Absorption... I hate the RNG nature of these spells, but it's not that bad when you are the one casting them. So they're perfectly castable, and reaching something like 50 magnitude is certainly possible for skilled mages. Note that Spell Absorption will use vanilla values on absorb, which might look weird, but not crucial imo.

Soul Trap requires some skill, making scrolls more relevant. Since you could previously just use very cheap spells with short duration, it should be noticeable. Any decent Mysticism mage should be able to cast a long-duration spell.

Telekinesis is a fun little tool, and even more fun with Enhanced Telekinesis, which is supported. 1-second effects are cheesy and nerfed, and at high skill you can make some pretty high magnitude spell. Which can be useful sometimes. In TR there's a cave where you can grab a neat treasure, but only if you can reach it - through strong Telekinesis effect.

Teleport spells packs from Magicka Expanded are supported and recommended. It's another bit of utility helpful for Mysticism - and they are expensive. Teleportation is an advanced magic, Mages Guild makes a living out of it. You'll need to be skilled in Mysticism (60 skill or so) to cast them. Teleporting around the map for free ain't free.

Restoration

Restoration is a defensive/supportive spell school with some utility and zero offensive effects. Magicka of the Third Era expands on it's buffing capabilities. If you're using summons or followers, Restoration gets even more attractive. Restoration already was a great supportive spell school, and it got even more, while even getting some stuff that allows it to be a main school... (Small spoiler ahead: there are three unique "holy" damage dealing spells)

Curing diseases is harder. Normal diseases can be cured by a lvl 1 player that majors in Restoration, but for blight diseases you'll need to get quite a bit of skill. Curing others is easier than yourself. I think it makes sense immersion-wise, and it also helps with some quests (like the early Imperial Legion quest, where you are tasked to cure a blight disease).

Curing yourself from poison is significantly harder! Honestly, I find this effect kinda broken. You could just cure yourself from all the poison DoTs for cheap. Not anymore, now it's somewhere between normal and blight diseases in terms of difficulty. Curing others is easy to reinforce the healer theme. Curing others from paralyzation is also fairly easy.

Restoring attributes and skills takes effort. In Vanilla, you could just spam cheap spells. In Magicka of the Third Era, you need to be at least somewhat skilled. At the same time, you'll no longer have to spam weak spells to fix your attributes, stronger spells will be more efficient if you can cast them.

Restore Health is now more biased around durational spells. Having a long regeneration effect is now totally viable. It now might be even worthwile to pre-cast such effect before battle and wait for Magicka to regenerate a bit. This is even more impactful for targeted spells, so you can have powerful spells that heal others over a long duration. Instant heals can still be worthy in case of an emergency, but are quite expensive.

Restore Fatigue behaves in a similar way. Long-duration effects are much more worthwise, and even more so for the targeted spells.

Restore Magicka, obviously, is out of the spellmaker. It is still present in some unique spells, but that's it. It could be balanced with some huge durational biases, but I think premade unique spells are enough.

Fortify Magicka is a very strange effect that I've also banned from the spellmaker.

Fortifying Attributes, Attack, Health and Fatigue, however, are now quite abuse-free and powerful tools. You can buff yourself for a reasonable duration, and it works even better for companions. At the same time, effects with duration of less than 20 seconds will have the same cost as effects with that duration, eliminating the case of powerful 1-second buffs.

Fortifying skills is not allowed in spellmaker. As with Absorb, it's a bad design for most skills. With spell schools, the problem is obvious, you can bypass many limitations and create tons of loopholes. With non-combat skills you essentially bypass your character limitations and give yourself absurd speechcraft or something like that. With combat skills, there are counterparts. For weapons, fortify attack. For acrobatics/athletics, jump/speed. For sneak, chameleon. The only somewhat interesting are armor skills (because they scale off your armor, unlike shield) and block. And these are restricted to unique spells. The alternative would be to keep this effect, but banning 80% of the skills, which would look pretty awful.

Resist 4 elements and magicka effects are tweaked in the way that reaching 100% is almost impossible, but master mages can reach 75 or so. It's much better for targeted spells, making for great buffs. Poison is notably cheaper and you definitely can reach 100% with it, just because you can always cure yourself with high skill anyway. It's still good against short-duration poison effects.

Resisting diseases... Did anyone use these effects? Now these are radically cheaper, so that having 100% resist for 5 minutes is still cheaper than actually curing the disease. It can now be a decent option if you still can't cure them, but can cast such long-duration buffs. Although imo these are still mostly pointless and I am baffled at how many of such spells there is in the game.

Resisting paralysis has it's uses and it's slightly cheaper than resisting elements. It's a niche, anyway. But maybe it will be of use sometimes.

Finally, resisting normal weapons. I wasn't sure whether I should allow it to be spellmade. But it probably won't break anything, so why not? There are now a couple of unique spells through which you can get this effect and play around with it. It's probably very niche.