I definitely agree with all above.
All direct damage spells should have some secondary effect to them tomake them interesting.
Also summoning magic, should have summons, which are not only different by strenght but also they should have different unique abilites (spells) , which fit certain situations.
As was said, I am also missing spells like fire shield, teleport, mana shield, healing overtime, knocback etc...
And what make me sad most is, that we can not alter terrain in tactical battles, but we can on the map, that would be soo cool, if we could make hills, which would take longer to pass, or water which is unpassable, or other terrain features, which provide bonuses
general rule is:
Fire: High damage, AOE, Damage overtime. attack buffs
Water: Healing, Spell Protections, buffs (Liquid form, water walking etc), dispels
Air: Electrical dmg with stuns,knockbacs etc... speed buffs, ranged protection
Earth: Meele protections, Slow debuffs, Defense buffs, DD spells and AOE spells with slowing effect, also earthquake and similar spells.
I would also like to see possibility to play as a summoner in battle...Or something similar to necromancer, rising army from death troops, with full of curses.