Lots of fast moving power chords, but as the 'D' tuning lets you make a power chord with only one finger flat over one fret, the trick is to find the best arrangement of your fingers. Learn your way around the notes first by playing it with only one string, then flatten to power chords.
There are quite a few slides, mostly downwards, when sliding a power chord make sure you give it a solid squeeze and in this case shove it quickly. What makes the riff sound even more impressive is the sudden high/low/high jumps, but this is actually easy because the low note is the open D string.
VERSE single string
E [-----------------------------------------------------------------
B [-----------------------------------------------------------------
G [-----------------------------------------------------------------
D [-----------------------------------------------------------------
A [-----------------------------------------------------------------
D [-0---11--12--0---11-\-8---0---8---0---8-\-7---0---8-\-5----------
CHORUS flat powerchords
E [-----------------------------------------------------------------
B [-----------------------------------------------------------------
G [-----------------------------------------------------------------
D [-0---7---8---0---8-\-5---0---5---0---5-/-7---0---7---4-----------
A [-0---7---8---0---8-\-5---0---5---0---5-/-7---0---7---4-----------
D [-0---7---8---0---8-\-5---0---5---0---5-/-7---0---7---4-----------
P.S. You have just being using the 'Byzantine' scale.