Me and my group of friends have collectively put in a few dozen games so far and we've come to the consensus that the mountain giant is one of the more imbalanced figures. We play with all the expansions that I know of except for the Hili expansion, and also usually play with the wolfman removed as we see that as another unbalanced figure.
The Mountain giant seems to warp all of our games as they get pushed to be ore tempo focused anddoubling up on the lord of ____ cards gets out of hand really quickly.
If I had a nickel for each post about a card, combo, or strategy being overpowered... I could buy a kickstarter version off ebay.
I think we can all agree that everything is overpowered and the game is pretty balanced.