When trying to cast or come over the top with this club, you will feel a sharp flex in the shaft at the top of your back swing when you initiate the down swing. Once this club flexes it will not recover. Therefore, the flight will be the same as that of your regular club but a bit more exaggerated. Now that you have felt that flex in your swing, you will concentrate on eliminating that flex, at that point in your swing, on your next shot. Don't expect the flex to go away immediately.
Old habits are hard to break.
If you really pay attention to what TWTM is telling you, you will expedite the process of eliminating this action. Also, check your swing path. If you are, it is hard not to come back over the top. Work on taking the club to the top so it will be toe down and parallel to the target line. Then I start into the ball with my hips and shoulder turns being sure to use my leg drive for power.