Sonic, Tails, Amy, Knuckles and you have been battling Dr. Eggman and Metal Sonic. Using a strange gem, Eggman has vastly upgraded Metal's power, allowing the robotic double to overpower all of you. The city is reduced to rubble, the heavy rain mixing with you and your allies blood, Sonic was the only one fast enough to evade Metal's energy beam, the rest of you are barely alive. Sonic can't stand seeing his friends so injured, he grits his teeth, clenching his fists, the Chaos Emeralds appear.

The Chaos Emeralds surround Sonic, but it's so different from his usual transformation into Super Sonic. The Emeralds go black, Sonic, angered, feeds off their negative energy. His quills raise upward, fur turns black, and he loses his pupils. A violent purple aura surrounds him as he stares down Dr. Eggman and Metal Sonic.