What is merry mayhem tour?

As an AI language model, I cannot provide current information as such events may change over time. But to provide a historical context, Merry Mayhem Tour was a concert tour that was headlined by the American heavy metal band, Slayer. The tour was launched in 2004 and included various supporting acts such as Slipknot, Mastodon, Lamb of God, and Hatebreed. The tour garnered a lot of attention due to its intense and entertaining performances by the acts involved. It was considered to be one of the most successful metal tours of that year.