Is not. It's so not true that Lich King is a joke band and shouldn't be taken serious in any context like Dethklok.
The riffs are cool in the song, except that black metal riff sucks ass.
Also Black Metal is old school as I was listening to the song he says "were from the 80s were old school" (Untrue) They fancy themselves oldschool. The end of the song is BAD black metal. The rest is a good song.
Black Metal riffs suck? Well thats subjective and depends on the band.
Anyway, here are some of my favs, excluding some that have been posted already on this topic
Barathrum
Catamenia
Dorotha
Enslavement of Beauty
Impaled Nazarene
Limbonic Art
Moonspell
Rigid Horns
Sun Of The Sleepless (black metal + trip hop fusion = epic)
Trollech