To effectively return a serve with heavy backspin, focus on your paddle angle and timing. Position yourself to read the spin and anticipate its impact on the ball's trajectory. Open your paddle slightly by angling it forward to counteract the backspin, making sure to hit the ball with a firm, flicking motion rather than a flat stroke. Aim to strike the ball early, just after it bounces, using a short, controlled swing to lift it over the net while generating a bit of forward spin or hitting with enough power. By maintaining a relaxed grip and good footwork, you'll be able to adapt quickly and place your return strategically.