First of all you hero rocks
Now i would suggest only one thing:
Balance him out, dealing 300 damage with one spell is enough to kill a massive army of footman, i know that you may think mountain king has a even stronger spell, but you hero has all AOE spells so if i were you i would have weakend him a bit.
Also this is a hero contest be sure to balance his health, mana, armor, speed and damage else if he has insane mana regen and mana amount you won't get balance points.
Hope this helps and again nice hero u got there ^^