Following the announcement last week that Dimmu Borgir have parted ways with bassist Vortex and keyboard player Mustis, the band have issued a scathing update via their MySpace blog.Referring to Mustis, the band poked fun at him for allegedly forgetting to take his instrument to a major European festival."Lesson number one, the obvious one: Don't forget to bring your instrument when you're about to play a festival in which you're going to perform in front of thousands of fans that have travelled far and paid money to see you play. "Maybe you haven't been into it so much the last couple of years," the post continued. "And it's - on top of that - an early flight; you feel things are a bit tedious - no worries, we all experience this from time to time but we know the deal by now after so long, and so many years. Or, so we thought. But, we shouldn't have to remind you to bring your own instrument to a gig. For that there's no excuse, neither will we accept one."