What elevates a heavy metal concert above just listening to the album at home? Well – apart from the sheer, skull-crushing noise – it’s the fact that anything can happen. And few things prove this to be true more consistently than the impromptu guest appearance. At a live show, you can see your favourite band collaborate with one of their (and/or your) idols, or an up-and-comer prove their worth with stars of their genre. So, Hammer’s compiled the best live team-ups in heavy metal history, from all of the Big Four in one place to Killswitch Engage re-embracing a former frontman…
