Feral Mount- mounted units lose 50% att/def/movement
I like this idea but why not have them actually lose control of the unit for a few turns.
Freeze Metal (Water - Level 2) - Unit wearing metal armor suffer damage from contact with cold metal. Does not affect units wearing leather armor.
Also a cool idea. For simplicity sake it could just do extra damage based on the targets armor.
Spells that target every unit on the battlefield (like Heavenfall's concepts). These would be especially fun with the new comparative modifiers.
Ya that would be great. Would add a ton of tactics and really make unit design count.
Windstorm - All units with over 20 Initiative lose -2 Initiative, and all units with over 24 Initiative lose and additional -1 Initiative.
Fiery Sun - All units with over 20 armor take 1 fire damage per unit per turn.
Also I'm thinking any rain spells should boost electrical damage. 
My personal peeve with tactical summons is I how they don't scale. I would love the ability to summon creatures in groups based on that players maximum unit size and weapons. Here are some unique ideas for tactical summons...
Avenging Armor: Life Spell. Enchant target friendly unit and upon its death a group of ghosts units, you can only see their equipment, of the same size and with the same items is summoned for the rest of combat.
Tree of Life: Summons an immobile tree that heals an ally every turn.
Death Curse: Death Spell. Enchanted enemy unit takes 1 damage per unit per turn. Upon death a Death Demon is summoned under casters control.
Reanimate: Summons a group of skeletons with group size and weapons equal to last group of trained troops that died. Okay ya I know but I'm just brainstorming.
Summon Warg Pack: Summon a group of Wargs at caster's level with group size equal to that player's max group size.
Lightning Rod: Summons a immobile lightning rod with a ranged lightning attack.
Wall of Thorns: Summon a 3 tile adjacent line, think cleave, of immobile thorns with a weak melee attack.
