Metal Madness is the first phase of the final boss of Sonic Heroes. After Neo Metal Sonic copies the heroes data and combines it with that of Chaos, he transforms into this twisted metal monster using pieces and components from the Final Fortress. In this form, he is fused to the Fortress and attacks Teams Rose, Chaotix and Dark (in that order) as they try to buy Team Sonic enough time to use the Chaos Emeralds. He has a number of different attacks: he can launch the claws on his left arm like rockets, launch the spines on his back to freeze enemies, smash enemies with his long tail or incinerate them with the flamethrower on his right arm. After the heroes destroy the three devices binding Metal to the ship, he produces two large skeletal wings and takes flight as the Metal Overlord.
When the Metal Overlord takes flight, Sonic transforms into Super Sonic and shares his power with Knuckles and Tails. The three pursue Metal Overlord into the clouds, who attacks them with his freezing claw-rockets, spine missiles and crystallized energy blasts fired from his torso. He can also throw whole Egg Fleet battleships at the heroes to slow them down and has even copied Shadow's Chaos Control ability, which let's him warp time and space. Even with all of these powers, Metal overlord could not defeat Team Sonic, who used their Super Team Blast attack to bring him down. After being defeated, Metal Sonic reverts back to his original form and shuts down.