'Heimdallr' was very interesting for me. The lyrics are static descriptions of the Norse God, screamed over blasting passages that emphasise intensity and energy at every moment. It's quite contradictory. Listen to that solo. It's very simple, merely ascending, only to create the illusion that the song is getting faster to an extent that is really beyond the musicians' capabilities. Then the song goes quiet on the vocal/lyrics front, and the other instruments enter a slow transitional phase before that beautiful melodic riff, which is like the conclusion of the song. It really sounds like the music is becoming Heimdallr (if that makes sense), with the opening riffs idealising a warlike struggle through life in order to become more like a god, calling out to Heimdallr as that archetypal deity in particular. During that transitional phase, the bass creates this very hollow effect that resembles 'going beyond' that material struggle and the final riff is acheiving the state of Heimdallr. Then the song returns to the battlefield, only, the last enunciation of 'Heimdallr' is extended as if to say this process of overcoming is ever ascending.
The other songs work in a similar way, but 'Heimdallr' is the simplest, and the 'dynamic' of the lyrics are so opposed to the nature of the music, so it's easier for me to explain! I think 'Hordanes Land' is quite similar in how it is all about experience and immersion. The first song begins with the simple keyboard riff to create the effect of breathing, which is then put into a context of violence and harsh nature by the Metal instruments, and then the proto-Heimdallr battle riff follows. After all this is a slow riff that creates a similar effect to the change of pace in 'Heimdallr', like transcending. Then the song returns to the battlefield, with the original keyboard riff turned into an amazing lead that sounds like a bird flying over the violence below. Then, interestingly, a triumphant riff closes the song but only for so long, hinting that there is no final victory, but only higher ascendence.
It's becoming one with nature to become a kind of superman. For me, I don't think Metal has been so profoundly inspiring.