This Bathory guitar riff, from the song Dragon's Breath, is mostly 8th notes, and is in the aeolian mode. The 2nd to last note shown in this riff changes the mode to phrygian, giving a darker sounding finish to the riff.
This song is tuned down two whole steps.
Here is Guitar Pro 6 tab for this riff:
John Taylor - guitar and bass instructor for Mile High Shred.