I definitely agree with all above.

All direct damage spells should have some secondary effect to them tomake them interesting.

Also summoning magic, should have summons, which are not only different by strenght but also they should have different unique abilites (spells) , which fit certain situations.

As was said, I am also missing spells like fire shield, teleport, mana shield, healing overtime, knocback etc...

And what make me sad most is, that we can not alter terrain in tactical battles, but we can on the map, that would be soo cool, if we could make hills, which would take longer to pass, or water which is unpassable, or other terrain features, which provide bonuses

general rule is:

Fire: High damage, AOE, Damage overtime. attack buffs

Water: Healing, Spell Protections, buffs (Liquid form, water walking etc), dispels

Air: Electrical dmg with stuns,knockbacs etc... speed buffs, ranged protection

Earth: Meele protections, Slow debuffs, Defense buffs, DD spells and AOE spells with slowing effect, also earthquake and similar spells.

I would also like to see possibility to play as a summoner in battle...Or something similar to necromancer, rising army from death troops, with full of curses.

1000+ Maybe?

I can already see that which mod will be one of the most popular mods: The Libram of Thousand Spells

Some really cool spells in there. I especially like the 7 deadly sins enchantments.   But...

I think the spellbook needs to be better structured. Right now it seems like a bunch of books with random spells in them. Fire Elementals are in Summoning instead of Fire. Ruin and Restoration have the same spells in them. Magic domains (Fire, Life) get mixed up with different types of spells, i.e. Enchantment or Summoning spells are something that every domain should have. "Combat" shouldn't be a book of its own either since all kinds of spells are used in combat, including Fire, Ice, Ruin etc.

Having a well structured magic system is essential. 

My suggestion: separate magic domains and spell techniques.

7 DOMAINS to cover all sources of magic

• Fire, Ice, Air, Earth (4 elements)
• Creation and Ruin (life and death with possible Divine associations, Creation just sounds more epic than Restoration to me)
• Spirit (magic energies, mind magic, mana related and all things incorporeal)

Domains dictate what powers the Sovereign wields. Domains are connected to power sources like Shards. There should be a way to specialize or generalize in them as you please. Like Master of Magic.

3 TECHNIQUES to categorize spells

• Invocation (bursts of energy, combat magic, instant damage/healing)
• Conjuration (summons, permanent creations)
• Enchantment (lasting magic effects, buffs, debuffs)

Techniques dictate what kind of spellcaster the Sovereign is and how he wields his power, i.e. Summoner, Battle mage, Enchanter or Archmage. These can be talents to pick that specialize you in certain types of spells. Perhaps only choose one at Sovereign creation to make the choice meaningful.

Every individual spell would be a combination of domain and technique. The pros of this system are that you could easily create a spellcaster with exactly the kind of focus you want. Want an all powerful Fire mage who can incinerate things both on the global map and on the battlefield? Specialize heavily in Fire. Want a Battle mage who can blast away on the battlefield with different elements like no other? Pick several elements and specialize in Invocation. I'd also add a Global tag for global spells just in case. 

More importantly, these domains and techniques would cover any spell imaginable that could be added later in expansions. So instead of adding the 50th Book of Whatever you would have a functional structure to place new spells in. There would be no overlapping of spells and these 7 domains and 3 techniques would be a very clean cut imo. Simple enough yet very flexible.

Examples of spells:

• Fireball (Fire / Invocation)
• Summon Fire Elemental (Fire / Conjuration)
• Wall of Fire (Fire / Enchantment)
• Rain of Fire (Fire, Enchantment, Global) - permanent rain of fire above a city
• Meteor Storm (Earth, Invocation, Global) - calls down a meteor storm to bombard a city once
• Eldritch Blast (Spirit / Invocation) - blast of magic damage
• Arcane Shield (Spirit / Invocation) - globe of force protects caster for a short time
• Spirit Blade (Spirit, Conjuration) - summons animated blade and armor
• Charm (Spirit / Enchantment) - takes control of target unit
• Mana Flux (Spirit / Enchantment, Global) - all spells cost more mana
• Heal (Creation, Invocation)
• Summon Ent (Creation, Conjuration)
• Entangle (Creation, Enchantment) - roots entangle enemies
• Divine Radiance (Creation, Enchantment, Global) - boosts morale, weakens undead
• Drain Life (Ruin / Invocation) - steals life
• Aura of Weakness (Ruin, Enchantment) - AoE weakness on battlefield
• Summon Shadow (Ruin, Conjuration)
• Nether Gate (Ruin, Conjuration, Global) - creates a permanent gate with undead pouring through every turn
• Gluttony (Ruin / Enchantment, Global)
• Eternal Darkness (Ruin, Enchantment, Global) - lowers enemy morale, empowers undead

I think you also need more ways to balance the reusage of powerful spells (which there do not seem to be a lot of really world changing ones anyway).

Consider making the mana regen of the sovereign an important stat and make some spells take multiple rounds to cast until you have poured all the mana needed into them. Because, as another person already pointed out, the Spell of Making taking 20 mana and instantly cast is quite anti climatic. So that powerful spell took only the same amount of mana as enchanting the farms of two towns?

What you could do is have a class of powerful spells which are not instant but have to be built up over several turns in a shard. If you interrupt, the mana already spent is lost.

Teleport on strategic map costs only 1 mana??? 

This is probably the first thing that I'll mod out of the game (increasing mana cost to something like 10 could work too, but I think I'll just remove this spell altogether).

You asked for it! Here are some thoughts for strategic spells.

Pack Ice:  Temporarily enchants one or more ocean/lake squares to temporarily freeze, allowing armies to pass over it. Any land units in the square when it thaws are lost.  Any naval units in the square when it's first cast are unable to move until it thaws.

Part Waters:  Enchants one or more ocean/lake squares to temporarily become land, allowing armies to pass through.  Any land units in the square when it ends are lost.  Any naval units in the square when it's first cast are lost (or maybe just moved to an adjacent water square?).

River Spirit:  Enchants a river (or specified river squares?) in the sovereign's territory to react violently to hostile forces that cross it (think of the river scene in Fellowship of the Ring).  All hostile forces crossing the river sustain damage/losses.  No effect on friendly units.

Impenetrable Forest:  Enchants one or more forest squares to become extremely overgrown and tangled, increasing the movement cost for all land armies moving through it.  (If the enchantment is invisible to opposing factions, the caster could even pick the tiles in such a way as to leave a "safe" path of unenchanted squares through the forest that only he/she knows.)

Tempest:  Enchants an area (or global?) with strong unpredictable winds.  All flying units are treated as non-flying.

Torrential Rains: Enchants an area with unrelenting heavy rain.  Terrain in the affected area, including roads, becomes a muddy quagmire, increasing the movement cost for all land units.  Rivers becomes swollen, inflicting damage/losses on any land units crossing them.  Movement penalty and river damage affects all units - be they friend, enemy or neutral.

Blizzard: Enchants an area with heavy snow.  All land units suffer severe movement penalties and sustain damage/losses.

Enveloping Fog: Enchants an area with thick fog.  Visibility range for all units is reduced to one.

Wildfire: Ignites a highly contagious fire in a single square, which can spread to neighbouring squares, and so on, up to a maximum total number of squares.  Destroys forest/grassland/etc, but cannot spread to mountains/desert/water.  Inflicts heavy damage to any city to which it spreads.  Can be extinguished by appropriate spells (e.g. Torrential Rains, Blizzard).

Landslide: Affects any square adjacent to a mountain square.  All units within that square sustain damage/losses.

Hmm, as for some tactical spells to control the battle in more subtle ways...

Rift: Opens a crack in the ground several squares long.  Non-flying units are unable to cross it.

Buffeting Winds: The battlefield is affected by strong, unpredictable winds.  Ranged units suffer penalties to accuracy/damage/range.

Entangling Vines: Vines sprout from the earth and entangle the unit.  Unit is unable to move, but can still fight (perhaps at a penalty), until it frees itself.

Trance: Affected unit becomes distracted by phantom visions, and is unable to move or attack for a number of turns.  Attacking the unit breaks the spell.

Death Pact: While in place, the caster gains mana (health?) from every death on the battlefield.

Summon Vengeance Demon: Summons a powerful demon which needs constant control.  Caster is unable to do anything else while they maintain control.  Damage to the caster causes them to lose control, in which case the demon prioritizes the caster that summoned them as their next target.

Bind Demon: Attempts to establish control over a demon.  Could be used to attempt to regain control of a Vengeance Demon (though without guaranteed success), or maybe even steal control of an opponent's demon.

Mirror Image: Multiple copies of the caster spring into being.  These have no attack value or separate abilities, but are indistinguishable from the original.  Attacks against the caster have equal chance of hitting any copy or the original.  Hitting a copy causes it to disappear.

Wildfire: A tactical version of the spell I mentioned in my earlier post.  Starts on a single square, but spreads in random directions.

Awe: Any unit attacking the caster risks being overcome by the caster's perceived magnificence and is unable to attack them.

One of the requirements for v1.0 available spells is that the AI has to be able to use them.

It's really cool (and easy) to come up with really cool sounding spells. It's not even hard to program them in for the player.  But getting the AI to use them effectively (or at all) is another case.

Post release when I have a lot more time to play with the AI, I can look at more sophisticated spells.

Ideas aren't the problem. Getting the AI to use them is.

At my advice, this original spell list + the content of all other « secret » books will allow us to have a lot of possible tactical choices for the version 1. Don’t forget that this game contains an incredible amount of systems, features and choices; more than any game that had been released over the last years.  We can’t ask for the moon (and 500+ spells) for the release, we will create our own spells with the modding tools, and receive more in the upcoming versions and expansions.  This game has an incredible potential, and it’s really designed to grow over the following months/years. We must take in consideration that the development team seems to have put all their effort to create a game incredibly customisable, so in the following weeks / month after the initial release, we will see a bunch of new spells, systems and mods.

My 2 cents, fell free to comment

I think everyone with massive amounts of spell ideas should be sure to read this.

As for the direct damage spells, I think the easiest way to make them more interesting is add some situational use to them. Perhaps Spell A does damage to all in a line, while Spell B bounces from unit to unit up to a maximum number of hits. Adding effects like this don't seem too complicated for an AI to use appropriately.

There are some spells I saw missing that I'd like to see, though. What about City spells, both offensive and defensive? I see a lot about altering production and resource rates, but how about Wall of Ice protecting your city in a wall of ice, giving added benefits against Fire magic or something?

Overall, the spells above look like they'll be a lot of fun to mess with and I can see the potential for fun combinations. I have 2 suggestions I hope you consider, though.

Weather: It would be nice if we could throw a Thunderstorm over an area (Random chance of damage?) or cover a grassland in snow, temporarily hindering movement.

Items: Custom enchanted items. I haven't seen much about this, but I remember spending far too much time making nice equipment for my Heroes in MoM using the Create Artifact spell. Did I miss it? If not, please consider this. I'd love to be able to take my Sovereign and create the Naysayer Battle Axe for his daughter before she leads the army against their enemies.