Having listened to the new Watain record religiously lately, I was reminded of this little exchange between Watain and Damnation a while back.
Peter Stjärnvind (of Nifelheim, Krux, Entombed, Regurgitate, Unanimated, Merciless, Face Down and Murder Squad) and Richard Cabeza (of Dismember, Unanimated, Dark Funeral and General Surgery) formed Damnation back in 1989 and were originally a Bathory tribute band, which should give you an inkling of what their idea of black metal sounds like.
While they released a demo in 1994, it would take them another ten years before their first album Destructo Evangelia was released. E from Watain provided vocals for the title track:
(mp3) Damnation - Destructo evangelia
Available on Destructo Evangelia (2004)
And a couple of years later Stjärnvind returned the favor by doing some vocals for Stellarvore, the closing track on Watain's Sworn To The Dark:
(mp3) Watain - Stellarvore
Available on Sworn To The Dark (2007)