When two of rock’s biggest acts descended on Montreal on Aug. 8, 1992, fans anticipated a show for the ages. What they got was a riot. Metallica and Guns N’ Roses were in the midst of a North American tour when they arrived in the Canadian city. Metallica would be the first of the co-headliners to perform, but things took a dangerous turn during their set. As the band performed “Fade to Black,” frontman James Hetfield was injured in a pyrotechnics accident that left him with second- and third-degree burns. Metallica immediately ended their set and rushed the singer to a hospital. Fans would ha…