This is a world of magic.
We can lower mountains, and drown them down.
Why a sovereing is unable to make the place inhabitable with spells, if that's even the first chapter of each kingdom/empire when a sovereign settles?
Would it be too OP?
How about 200 Mana spell, add +1 material to the spot, or +1 grain. or 350 mana +1 essence?
doubel that for increasing from +2 to +3 and further or whatever, it's a matter of balance, but why we are unable to do so?
Human mages would be able to create places for cities.
Why a fallen cannot build a city on ruins of other city? That razing thing stuff, is strategically fine, as long as there is a counter, there should be a counter for everything to form a good game I think. so maybe just reducing the place by -1 material/-1grain?
Why a city cannot be formed on 0/0 place? you could still rush some building to get the production going.