Complex sentence: The tour included 341 concerts around the world with headlining shows, festival dates like Download Festival and Mayhem Festival, Opening act for bands like Iron Maiden, Avenged Sevenfold and Trivium.
Split into simpler sentences: The tour included 341 concerts around the world with headlining shows, festival dates like Download Festival and Mayhem Festival. They also preformed as an Opening act for bands like Iron Maiden, Avenged Sevenfold and Trivium.