Mastodon have been confirmed for Download Festival 2013 by Andrew Copping on Twitter. This news comes only days after the announcement that Stone Sour have also been added to the bill. With Slipknot headlining the Friday night Download 2013 is shaping up to be an unmissable line-up. Mastodon will be playing the Main Stage on the Saturday of Download under Iron Maiden, QOTSA, Motorhead & Alice In Chains.