Warthur
This one's a bit of an oddity. Released as part of the promotional work preceding the release of Heritage, the title track is one of the studio cuts form that album, which saw Opeth take a hard turn away from their metal roots into more purist prog territory. However, by far the bulk of the material - and what most Opeth fans will be interested in - is their live appearance from 2009's Rock Hard festival, which would have been in the wake of the release of Watershed. As a result, you get a quick preview of what is essentially a whole new style for the band (though The Devil's Orchard is one of the more energetic tracks on Heritage) followed by a festival set played in the style they were about to shift away from.
I suspect a good many Opeth fans who track this one down will find themselves simply skipping the opening track most of the time - not because of any problem with its quality, but simply because if you're an Opeth fan who likes their post-Heritage direction, you already have Heritage, and if you aren't this ain't going to sell you on it, and regardless of which type of fan you are you're really here for the festival set, not the studio album track you probably already have heard on the album itself. Still, it's worth a listen, particularly to hear the band interpret some of their metal works live at the point when they had taken that direction of their sound about as far as it would go.