Either we'll kill them, or they'll kill us. :D
Cold is certainly a powerful element, especially with the "Rain of Arrows" spell, but:
- It's easily countered with antimagic on key units.
- They might have resistance.
If we're focusing on light magic, we'll only have time to cast that spell throughout the entire battle.
Mass Haste, Divine Punishment, Bless, Stone Skin... there won't be time for anything else.
By the way, "Armor Burning" can increase damage, potentially more than double, but it didn't help as much as casting light spells.
If you're attacking with a single, powerful spell, then for a knight, neither cold nor fire will be as terrifying as...
"Rain of Arrows" with beehives or sword walls.
If you manage to find 3 or 4 enemies, of course, and have those spells.
Plus, there's an advantage in that it doesn't really matter which enemies are in your cursed units. The main thing is to have a lot of these stacks in the enemy army for more targets for the "Rain of Arrows." :D
It's just very difficult to gather all of this, even in a long game, although it depends on the map...
I remember one battle where my elf had 4 enemies and the "Archer's Dream" skill, and I saw "Rain of Arrows" with beehives and sword walls, and the elf's spell power was over 70. That was truly intense. :D