Queshire
Auror
Ice is the element of protection, loyalty, defense, and counter attacks.
So, this suggests to me that the direct offensive options should probably be fairly simple. There's a lot of inspiration that can be found in video games. Off the top of my head there's the ice destruction spells from Skyrim or all of the Ice type moves in Pokemon.
With the counter attack part I can imagine stuff like summoning up a wall of ice to block an attack, shattering the wall and sending the shards flying at his foes or a freezing wind that dramatically increases in cold the closer you get to him. A foe smart enough to give up can survive, but if they charge they're likely to end up an ice statue.