I would say even more - why not introduce spells triggered by place/event etc.

spell que of sorts for cities, units, places, borders, resources etc...

a bomb would be awsome.

Some CoreItems.xml have modifiers such as these

      <GameModifier>
            <ModType>Unit</ModType>
            <Attribute>UseSpell</Attribute>
            <StrVal>Escape_Ability</StrVal>
            <Provides>Allows the unit to cast Escape, which allows you army to escape from tactical combat to your capital</Provides>
        </GameModifier>

I never tried using them inside a spell but its worth a try.

Sorry, I tried this awhile ago and it doesn't work. I just found the thread. You can have a melee apply a spell that applies a melee spell. For instance, having a healer strike an enemy. That enemy unit would then give +3Hp to any unit he hits. You can also make the melee apply a spell that applies a melee defense spell. So every time that enemy is hit, he will also take 3 fire damage from your spell. It's too bad we can't just have a spell apply a spell, but I can see why the devs had specific use given how the magic system is set up.