At the beginning of Green Grove Zone Act 3, Robotnik, displeased that his nemesis has discovered his plans, finally reveals himself in his Egg Mobile, which is equipped with a large metal spiked ball. After allowing Sonic a few seconds to collect Rings at the corners of the arena by lowering his vehicle closer to ground (but still out of range of jumps), Robotnik drops the spiked ball, which proceeds to bounce around, damaging Sonic upon contact. Sonic cannot stay still, however, since the ball does not bounce randomly, but rather gravitates toward him. After five bounces, the ball loses all momentum and stops moving. Robotnik lowers himself to retrieve his ammunition, but exposes himself to an attack. While the mobile is in range, Sonic must jump and land a hit on the vehicle, but avoid touching the dangerous spiked ball. If Sonic aims too low, he will be deflected by the Egg Mobile's size, or be damaged if he aims for below. Only direct shots at the glass cockpit will damage the vehicle. Once Robotnik has returned to his position high above the ground, he drops the ball again, and the process repeats. The Egg Mobile will drastically increase in speed when nearing defeat. After sustaining five hits, Robotnik flees the arena in his smoking vehicle.