Twenty years ago, nine inspired musicians from Des Moines, Iowa, shattered the scope of what was possible in rock music. From the moment Slipknot emerged in 1999 with their self-titled debut, it was clear they were like nothing the world had seen before, but were everything they needed. Where a similarly creative act might have burned out or lost their relevance chasing mainstream acceptance, Slipknot has only proven that an enduring commitment to hard work, constant evolution, their craft, and…