Complex sentence: DragonForce toured with Disturbed and Slipknot during the inaugural Mayhem Festival in 2008; the band then returned in autumn with the release of their fourth studio album, "Ultra Beatdown".
Split into simpler sentences: DragonForce toured with Disturbed and Slipknot during the inaugural Mayhem Festival in the summer of 2008. The band returned in autumn with the release of their fourth studio album, "Ultra Beatdown".