The song itself is really just the first act of the music video with the second act consisting of Nergal (lead singer) performing some sort of ritual. Can anyone clarify what he is doing?
Also, he keeps mentioning Akephalos, a headless demon. What does mentioning Akephalos mean in this context?
An artistic performance aimed to accompany the song, thus helping with the commercial success of the band.
I mean the title of the song is pretty obvious I guess. It is an ode to Satan. As far as I know Nergal is an atheistic thelemite (not sure tho) so he propably doesn’t actually worship demons. The song is a banger tho. My favorite behemoth track actually.
I love behemoth.
I speak polish so it hits a little differently.
But for me this song instantly pulls me to a place where they are.
I always have demons and spirits around me.
So it acts like a grounding music to get me closer if you know what I mean.
For me my favourite song is Lucifer by behemoth 
Well he’s just invoking Satan to force spirits to be as he says “be obedient unto him”. Typical stuff
Nergal is pretty awesome. There is a short documentary on YouTube called The Satanist of Warsaw about him.
My thoughts exactly
I really like some of their songs. Blow your Trumpets Gabriel is probably the only I like the most. I do like this one, though.
For the second part of the video, the phrase Lion - Serpent Sun appears in the book The Magick of Aleister Crowley according to Google. Some of the following sentences also match that.
However, some of the rest of it seems to be lifted from Senatorius Sacerdos Harpyiae’s Rite of Air.
Interesting question. Thanks for asking.
Akephalos means headless and is reference to the Headless One known better as Bronless One The Headless One by Jake Stratton-Kent — Hadean Press
It is an Invocation written by him, based on headless one invocation, with many references to solar gods and Liber AL. As said Crowley " Invoke often ! Inflame thyself with prayer !"
You can use it, enjoy 
This song is awesome and I am going to their next gig in Poland when corona ends. If you like that, listen to Dark Funeral “Secrets of the black arts” track as well.
Back in my delving into Satanism, this song really set the mood.
It feels like a straight up invocation