Warthur
Slayer followed up Reign In Blood, their fastest album, with a series of songs exploring the slower side of their sound - an aspect which, apart from a song segment here or there, they had almost completely neglected up to this point. Climaxing with an excellent cover of Judas Priest's Dissident Aggressor, South of Heaven sees the band really unpack their sound, using the slower pace to take the listener deep inside their intricately-constructed riffs to see how they're built. I don't think it is quite as essential as Reign In Blood, but it surely isn't very far behind at all.