The lower the points the game the stronger transformation is going to be. In 1000pt game its going to be incredibly strong as your essentially turning a 200pt wizard into a 500pt+ beast (finally found the profile for the "Great Fire Dragon, wow, i've never looked at that before, 8's all the way across). With 1000pts there is not going to be a whole lot you can do to deal with that other than dispel it, especially against elves because now you have an 8 attack dragon with ASF. And that 8 attack dragon is part of the unit... combat res anyone?