You know, it would be a lot easier to give advice and ideas if
you mentioned what effects you're going for.
A 'tiered' summoning of units, without spellcasting, is pretty
easy. One expensive unit has #domsummon of the first tier unit.
That unit has #domsummon of the next tier unit and so on...
This forces the player to keep the 'chain of summoning' intact while
still making the nation grow increasingly more powerful as dominion
spreads. So in effect you've got a research system based on praying
priests, though it's a bit clunky.
Attack spells can be simulated with either ranged weapons,
which uses ammo, or #onbattlespell using custom spells.