I am quite a builder and a roleplayer at heart, so often while playing strategy games i was very upset to see that you (the player) are able to wield enough power to cast something like an army- and country destroying armageddon spell, but are not powerful enough to turn this pesky swamp right at the center of your domain into something useful, like a plain or forest, let alone destroy a mountain.
This one resource you need desperately? Your arcane power rivaling the immortals cannot help you. Do not even try.
So i am going to suggest the often neglected non combat spells, quite a couple of them.
Since we do not know the terrain types, resources and city buildings yet, i will generalize and will be using some Civ4 and Fall from Heaven references.
Thinking about non combat spells i see different categories:
permanent, sustained, rituals.
Effects, cost mana/turn
example: Clearity of mind: as long as you are sustaining the spell your researchers are getting bonus points.
example: Bravery: your warriors know no fear, morale boni.
example: Vitalize: you envigorate the land, desert turns to plains permanently, no follow up costs.(FfH2)
example: Wall of stone: you cast it, get a stone wall in your city, end of story.
example: Spire of brilliant thought: building, grants "Clearity of mind" to the city it is created in. (mana + essence)
can be permanent or sustained, require production, can require additional ressources, sacrifices etc.
example: Vitalize Land: ALL tiles in your empire are vitalized (get one step better) permanent
example: Time Stop: Only you are able to take turns, sustained, massive upkeep.
example: Summon undead horde: sustained/permanent, as long as you are sustaining the spell the massive horde of undead you summoned is under your control, the dark energies are even healing them for a fraction of their HP each turn, as soon as you are not sustaining the ritual any longer they begin to crumble, losing fraction of their HP each turn.
So far my concept, Now, on to some more spells:
Please, please, please give us some GOOD terraforming!
The whole vitalize line: ice/desert through tundra, swamp, dead terrain, hell terrain, whatever to plains and merry meadows!
If base terrain and improvements are different let there also be spells for that too! Even for boni, but they should be costly enough to be a severe investment, but we have essence - non renewable resource- exactly for that!
/ice/hell terrain/dead terrain/ to /tundra/desert/ to /scrub plain/ to /plain/
/plain/ to /scrub plain/ to /tundra/desert/ to /ice/hell terrain/dead terrain/
deep water to shallow water to plain to hill to Mountain
Mountain to hill to plain to lake to sea
young Forest/Forest/ancient forest
young Jungle/Jungle/ Jungle thicket
Destroy vegetation (the reverse)
Motherload: you create a in a nearby mountain (massive costs + essence)
Living Gold: as long as the gold resource is in your sphere of influence you can move it (near a city f.e.) for massive mana cost.
Buildings in the cities which would permanently grant otherwise sustainable effects:
Fountain of life: big reduce of unhealthiness in the city + extra food + extra healing.
I will stop for now, the post is too long already, please write what you are thinking about the idea so far.