That slow, heavy, fuzzy riff needs a dark tone. Use a fuzz or Big Muff into a slightly overdriven Vox or Marshall.
Signal Chain
Big Muff Pi→Vox AC15→1x12 Alnico Blue→Output
PedalBig Muff Pi
gain
6
tone
4
level
6
AmpVox AC15
bass
6
gain
5
treble
5
presence
4
Cab / IR1x12 Alnico Blue
micRibbon
mic positioncenter cap
Notes
Keep the tone dark and mid-heavy. The riff should feel heavy despite being slow.