I really want to see a Frost mage! With atack spells like blizzard etc. The effected monsters would gain slow, if they already have slow then the stun condition. Moreover each monster entering the affected terrain would gain slow or roll less atack dices.  Spells that make monsters frozen. Being frozen doesn't necessarily means "stun". Maybe they cannot attack for one round or roll less dices or slow or a combination! However their armor as long as they are "frozen" should be increased! His monsters will be immune to frost damage. He should have equipment to make him immune to frost terrain effects. You can combine frost with water. If a monster had been attacked by a water attack earlier in this round, the frost damage would be greater!

If in the same round a creature has been attacked by a hydro attack, the frost damage will be larger. Terrain with snow, where creatures with no immunity to frost deal less damage. Or maybe become slow.
I really want to see a blizzard attack spell!