Swedish progressive metal stalwarts Opeth's 10th album Heritage -- which follows 2008's Watershed and 2005's Ghost Reveries -- is their strangest, most genre-melding to date. For starters it includes guest spots from Swedish flautist/composer Björn J:son Lindh and Weather Report percussionist Alex Acuña. As you may have guessed, it also includes 100% clean singing. Main man Mikael Åkerfeldt refers to ...