Imo, enchantments should be balanced as follows:

Inspiration - +1 reseach/essence - 10 mana cost - extremely useful and well balanced.

Meditation - +1 mana/essence - 10 mana cost - extremely useful and well balanced.

Enchanted Hammers - +1 materials - 10 mana cost - acceptable if low unrest, but balanced.

Sovereign's Call - +1 growth/essence - 20 mana cost  - extremely useful and well balanced.

Oppression - 10% unrest reduction - 10 mana cost - extremely useful and well balanced. Don't underestimate the reduction of unrest. This gives your more production that having enchanted hammers with the higher unrest. Both in conjunction can be REALLY good.

Propaganda - +1 gildar/essence - 10 mana cost - extremely useful and well balanced. 

 

Bell Tower gives -10% Unrest and costs 80 production. For comparison, Herbalist gives 1 mana per turn and costs 176 production. Meditation can give you 2 mana per turn if city has 2 Essences. So Meditation and Inspiration are much better than Oppression.

I agree. Imho Inspiration and Meditation are overpowered. Propaganda is underpowered.

Really good idea with scaling the stuff with city level, I think the oppression would get out of hand though, same with enchanted hammers.
But I would rather test it like this.
(Edit: Enchanted Hammers and Oppression might get out of hand in a level 5 city, but dunno, never had a lot of those).

Also like your more averaged city enchant cost, they could later be changed a few mana up or down, but that is details (It would feel... silly if all city enchants would cost exactly the same, I think anyways).

Sincerely
~ Kongdej

Imho, all city enchantments should be moved to spell levels 2. Some are just so good to start with. If you move them to 2, it forces the player to spend more customization points in an area if they want the enchantment from the start. In addition, the first champion you find will most likely not provide you with another enchantment.

Speaking about design, they are simply available too early for too little cost.

I think we will see more general Unrest in games now that taxes are required in the early game. If they reduce the gildar from adventuring, it would be perfect. Since you have more Unrest, you have less research. The problem is that a city with essence goes Conclave. That means they get twice the building options for reducing Unrest to 0. This means they can produce more money and research in the early game. With the current balance, the right Sov setup gives you a great selection of starting bonuses, assuming you have essence. This puts too much pressure on getting a start with at least 2 essence to cast these starting spells and reduce Unrest enough to use Normal taxation. Your only way to start well is to get essence and a Conclave. There is no competing strategy. There needs to be a few factions that get a bonus to non-essence starts or at least some techs that give a clear advantage or viable strategy to choose Town or Fortress in the beginning. 

Assuming that the balance of starting cities is managed, spells need some balancing to fit into the current mechanics. Propaganda should be +2 Gildar per essence, as someone pointed out. This is because gildar now matters less in the new tax system. Inspiration and Enchanted Hammers work in different ways. Early on, Inspiration triples your research power, while Enchanted Hammers adds maybe 33% production. As the game goes on, the value of Inspiration matters less, because tech costs do not ever go up that high and city level does massive amounts of research on its own. Enchanted Hammers, conversely, increases in value, as PPM increases throughout the game. A single Materials can boost Production by 20 later on, which is extremely valuable, as it boost troop training and improvement construction. 

You either need tech costs to increase a great deal per tier of research, or you need to reduce the research done by city level 4 and 5, reducing Inspiration to +25% Research in kind. Either the costs need to scale better, or the amount of research done needs to be more incremental. Other than that, the system can't be well balanced with the other economic factors.

In terms of elemental magic powers, water and earth are too good in the early game. Death is never good. Life and Air does better as a second string of choices. Fire is just an afterthought. I suggest we bite the bullet and have some weaker early game options, with more powerful ones unlocked at the 4th level spellbooks. Those later levels are too sparse and offer little incentive economically. You could also do it by city level, but then it kind of ignores a good opportunity to help out the magic system.

the solution would be civ like

every new city add 10% unrest to the whole empire

so you cant rush build cities same as civ etc etc

I'd like to see spells tied to technology, with a few automatically provided regardless of spellschools, while several are granted only if you have both the technology and the appropriate school of magic.

For example at tier 1 research (lets say trinkets since you can't start with it) you get an inspiration type spell that doesn't scale. A bit further down the tech tree (tier 2 or 3) if you have water magic you also gain a research bonus enchantment that does scale. Enchantments scaling with city levels is likely to cause as many problems as it solves. I do like the idea that a 1 essence location would be worthwhile, but I would prefer if enchantments scaled based on research in the magic tree (better options become available) as apposed to simply revolving around the location you built on.