In my imagination, this leucistic stag is some kind of spiritual guardian of the tundra. His pale colors help him camouflage so that he cannot be hunted down. His unnaturally blue horns release an icy aura and drip with icicles. Worn around his antlers on golden chains are magical gems, as well as a piece of his own antler that he shed before he became a guardian. His strange hooves, as hard as diamonds, are capable of kicking up snowstorms and transforming water to ice if he so wishes.
This is all just in my head, though. Since it's your deer, you can do what you want. That was just sort of the idea behind the design. I really hope you like him