I think this could be a potentially good card for value mage, just like some people mentioned the Reno deck, but then again it's too weak in comparison to Syndragosa (and she has synergies with the DK).
This is a powerful addition to hand mage. If you start with Mountain Giant in your hand, you fill your hand back up in the late game. Oh, and why not play another Mountain Giant? You can also go Even Hand Mage with it.