Creation - for me this sphere should be all about boosting the builder-style gameplay. To that end, resource flexibility, production/gold increases and perhaps a source of defense
Animated Sentinel: creates a permanent, summoned golem that has the guardsman promotion and can build roads and mines. Give it a high defense value. Max one per caster.
Transmutation: gold to copper and back, iron to gemstones and back, incense to regents and back. This helps the builder to peacefully acquire missing resources and/or specialize a town for production or commerce. That and allows the incense dependent FoL and regent dependent Veil slightly more options in their resource acquisition.
Major Fabrication: creates a temporary building which increases the town's production by some percentage (50% or so) and improves the cities trade by a decent amount as well OR increases the number of trade routes. Units can be upgraded for half cost in this city. I'm borrowing inspiration from the DnD spell Fabricate which allows a wizard to produce large amounts of manufactured goods from raw materials, offering a huge industrial boon to the region.
Earth
Wall of Stone (kinda boring, maybe add an effect when it is cast outside of cities?)
- Have this spell create a fort when cast outside of the city. That's basically what it's creating in the city; besides having an adept spamming a generally unimpressive tile improvement seems suitably powered for a level 1 spell.
Enchantment
Enchanted Blade
Flaming Arrows
- I would like this ability to either offer a larger bonus OR allow the unit to bombard the enemy. As is, (non-elven) archers are outperformed by melee units so this spell needs to be disproportionately better to make up for it. That and allowing bombardment would make it more than just a numerical bonus to the unit while still fitting the theme.
Spellstaff
- I always felt this ability, while nice, was a little underwhelming. Maybe have the promotion also decrease the chance of a spell being resisted/increasing spell damage?
Force
Mage Armor: grants all adepts/sorcerers/archmages in the stack a withdraw chance OR energy resistance like stoneskin does (so they can run away, hide in fire or at least not suffer so much from other damaging spells).
Whirlwind (push)
Force Blade: creates an equipment (only one per caster) which increases attack strength and gives a big bonus vs melee since it ignores any armor worn by the enemy. Also acts as the blitz ability or magic resistance promotion. This equipment should never be dropped OR should be destroyed instead of picked up by an enemy to ensure the number of force swords available doesn't exceed the number of casters.
Ice
Frost: transform plains and grassland into tundra, transform tundra into snow (I think the Illians and the Doviello should be able to treat tundra as grassland and snow as plains (and maybe ice as normal coast/ocean), making this spell actually useful for them). Also, everyone wants the lands of the elves to be covered in trees, hills for the dwarves, hell terrain for the Infernals and desert for the Malakim. I think this would allow the "cold civs" to have a similar terrain difference because, let's be honest here, being able to spread terrain favorable to your race is awesome. This spell does necessitate additional changes to the Illians and Doviello to really live up to it's potential.
Summon Yeti: this unit should be the counterpart to the sandlion (make it really powerful for it's level but limit it to summons on tundra and ice)
Palace of Ice: when cast in a city it should build a temporary building that gives units built there cold protection, a big defense bonus to the city itself, act as another granary (good for preserving food) and maybe give some amount of money or happy to the city. If cast on a tundra or ice tile it should build a citadel. This is, after all, a level 3 spell and I think would synergize very well with the Illians, both mechanically and thematically
--Alternatively you could make the Ice 3 spell be Blizzard which deals cold damage to all enemies in the 3x3 or 5x5 area surrounding the caster.
Spirit
Courage
Hope
Trust (probably needs to be more powerful)
- I like the idea of this offering a bonus against war wariness and/or a bonus to your great people point generation. Maybe you could make it so the enemies of a leader with Trust are always willing to talk (instead of after X turns of warfare)?
Concerning evil priests healing: cure disease is fine and honestly I'm fine with them having heal. However, if they have Hastur's Razor instead then they can effectively heal but do so in an evil way. Think about it: more evenly distributed damage in a stack PLUS a unit with Medic 2 or 3 = very improved recovery time.