The Duel on the Halberd began when Mario attempted to save his friends from Sonic's plan. The duel would lead to the deaths of Link and Mario.
Link's Betrayal and Demise
After the final death of Black Doom, Sonic says to his teammates that they were ready to kill the smashers. Link finds this wrong, and turns to walk away. As he walks away, he is stabbed in the back by Meta Knight. Before Link could be fully killed, Mario appears out of nowhwhere and finds out sbout Sonic's plan to kil his friends. Mario prepares for battle against Sonic, as well as the badly wounded Link. The duel had begun, with Sonic finally killing Link, and fights Mario on the Halberd's floating platform.
Ganondorf, Meta Knight, Wario, and Bowser looked on as Sonic and Mario battle each other. The duo threw items at each other, including explosive ones. When they landed on the Halberd, the battle almost came to an end when Mario and Sonic were both low on stamina health. They continued to battle with explosive and powerful items. At the climax of the battle, Mario was preparing for a final blow, but Sonic interrupted him by grabbing and smacking him, and unleashes his down throw move, which was an ending blow. Sonic continued to crush Mario until the defenseless plumber fell out of Sonic's grasp and fell off the Halberd to his death. With Mario dead, Sonic and his teammates can kill the rest of the smashers, with Wolf joining Team Dark, replacing Link. The Great Hero Purge had finally begun.