Viking metal.
There they are. Go suck 'em.
Honestly, it's just because I'm lazy. It's easier to say 'Viking metal' than 'black metal with a Viking-related lyrical theme'. If you have an issue with that, see above re: balls, flaming, to be sucked (by you).
Also I got $20 that says if I referred to Amon Amarth as death (or even better melo/death) some coprophage is going to be all like "wtf Amon Amarth is viking metal u fagget" (sic). The internet is a Janusian prostitute. THERE, I SAID IT.
Besides, this is an opinion blog. I am beholden to no one but my own sweet self. So if I say Viking metal is a genre, it's a genre. If you want to argue that, please feel free to do so in the comments, pre-supposing if you do that there is an implied EULA which states that any comments left on Also, Wolves or any of its sister sites (probably also named Also, Wolves) are subject to minute dissection and probable sarcastic (yet witty) mockery by the creator and/or the entire internet. No saving throws.

