I have now defeated Gluth and Thaddius on Heroic in Hearthstone. That finishes the Construct Quarter and only leaves two bosses in the Frostwyrm Lair left for Naxxramas. To defeat Gluth, I used Very cheap Anti Gluth Mage (HEROIC) with guide and video. To defeat Thaddius, I used Basic Solver Heroic Thaddius. Both are fairly cheap.