The optimum way to take advantage of this minion is by playing a spell immediately after it to give it Stealth, then on your next turn play a spell to give it Windfury that turn for its attacks, then before ending you turn play another spell to make sure it ends up with Stealth again, and repeat. Obvious synergy is with stuff like Rockbiter Weapon. It has big potential, but it's also a very slow card, it takes a lot of spells to keep it going like this effectively, and if you want to play for a big, end-game burst, you're actually better off just going with Leeroy Jenkins + Windfury + Rockbiter Weapons.
Still not 100% on the balance, and I may end up making some minor adjustments to the numbers, but I don't think it's too far off. =)